Compiled from 10 sources; we haven't tested this product ourselves yet. How we research
Quick answer
The MUJI Gel Ink Ballpoint Pen is a capped, refillable gel pen with a frosted polypropylene body. MUJI USA sells it in 0.38 mm (10 colors), 0.5 mm (10) and 0.7 mm (4), lists it at 14 cm (5.5 in) and gives Japan as its origin. One refill fits both MUJI's cap and knock bodies.
On this page11 sections
The cap-type pen in Black 0.38 mm, to scale at MUJI USA's 14 cm.
Product facts
Product
MUJI Gel Ink Ballpoint Pen, Cap Type (0.38 / 0.5 / 0.7 mm)
$under $5 per pen (multi-packs divided by the count)
Ink colors
Black
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Notes on these facts
Made by Ryohin Keikaku Co., Ltd.. Made in Japan: MUJI USA's product details for the 0.38 mm cap-type pen give "Country/Region of Origin: Japan", and MUJI Japan's page for the gel ink refill lists 原産国 (country of origin) 日本 (Japan). We read both on October 21, 2026. Source. Price: example listing.
Colors: names per MUJI USA, checked October 24, 2026. The ten ink colors MUJI USA lists for the 0.38 mm cap-type pen; the 0.5 mm also comes in 10 and the 0.7 mm in black, blue, red and blue black. Tints were sampled from MUJI USA's product photos (the colored cap insert and refill). Tints are representative, not measured. Shops stock different colors.
Price bands are typical US retail, checked October 2026. Conversions to US dollars are approximate, at October 2026 rates (US$1 = ¥158 = ₩1,330 = NT$32.5 = CN¥6.7 = SEK 9.9 = DKK 6.7 = ₺49.6 = C$1.41 = A$1.43 = CZK 21.7; €1 = US$1.12; £1 = US$1.32; CHF 1 = US$1.21).
Key takeaways
MUJI USA lists the cap-type pen at 5.5 in (14 cm) long, made of polypropylene, ABS resin and steel, with Japan as the country of origin.
US sizes and colors: 0.38 mm and 0.5 mm in 10 colors each, 0.7 mm in 4 (black, blue, red, blue black).
MUJI Japan lists the gel refill at about 110 mm long and 6 mm across, with pigment gel ink, made in Japan.
In Japan, MUJI prices the pen at ¥120 (about US$0.80), an empty body at ¥40 (about US$0.30) and a refill at ¥90 (about US$0.60).
MUJI says any of its gel refills fits either the cap or the knock body, so the pen is meant to be kept and refilled.
What is the MUJI Gel Ink Ballpoint Pen?
It’s MUJI’s capped gel pen: a frosted, translucent body with a refill you can swap, sold in 0.38, 0.5 and 0.7 mm. MUJI is the brand of Ryohin Keikaku, the Japanese retailer, and MUJI USA calls it “our top-rated pen”. Its US page shows 959 reviews averaging 4.8 out of 5 (October 21, 2026).
The cap carries a colored insert that matches the ink, so the color is visible in a pen cup. MUJI USA says a special tip mechanism keeps the ink from drying out, and that the water-based ink writes smoothly without bleeding through paper. Those are MUJI’s claims.
MUJI gel pen specs
Spec
Value
Maker
MUJI (Ryohin Keikaku Co., Ltd.), Japan
Type
Capped gel pen, refillable
Length
5.5 in (14 cm), per MUJI USA
Materials
Polypropylene, ABS resin, steel (MUJI USA)
Tip sizes (US)
0.38 mm · 0.5 mm · 0.7 mm
Colors (US)
10 in 0.38 and 0.5 mm; 4 in 0.7 mm
Ink
Gel; MUJI Japan lists pigment gel ink (顔料)
Refill
About 110 mm × 6 mm, polypropylene tube (MUJI Japan)
Barcode (0.38 mm black)
4550002794262
Made in
Japan (MUJI USA and MUJI Japan)
MUJI doesn’t publish a weight or barrel diameter. Its US product details list the 0.38 mm pen’s nib as 0.5 mm, which looks like a listing error: the title, refill and colors all say 0.38.
The refill runs about four-fifths of the pen's length; MUJI says it fits both the cap and knock bodies.
Should you choose the MUJI gel pen 0.38, 0.5 or 0.7 mm?
MUJI Japan recommends 0.38 mm for small writing in planners, 0.5 mm for clear, legible writing such as addresses, and 0.7 mm for people who press hard. The 0.38 mm also has the full range of 10 colors in the US.
In the US, the 0.38 and 0.5 mm pens come in black, blue, blue black, red, orange, pink, purple, green, yellow green and light blue. The 0.7 mm comes only in black, blue, red and blue black. A finer ball also means a lighter line, which suits thin planner paper; see our Pilot G2 guide for how ball size changes the line.
How do MUJI gel pen refills work?
One refill fits both MUJI pen bodies: MUJI’s Japanese site says every color and size of refill works in either the cap or the knock body. MUJI USA says the same for its 0.38 mm refill.
MUJI Japan built its pens around this idea under the name 詰め替えるペン (“pens you refill”). It sells empty bodies in white, black or translucent, in cap or knock style, so a body can outlast many refills. Its Japanese list prices are ¥120 (about US$0.80) for a filled pen, ¥40 (about US$0.30) for a body and ¥90 (about US$0.60) for a refill.
MUJI Japan lists the refill at about 110 mm long and 6 mm across, and sells it singly in each color and size.
How does the MUJI Gel Ink Ballpoint Pen compare to the Pilot G2 and Zebra Sarasa?
The MUJI pen is the capped, minimal one; the Pilot G2 and Zebra Sarasa Clip are retractable and sold in more US stores.
MUJI Gel Ink (cap)
Pilot G2
Zebra Sarasa Clip
Mechanism
Cap
Click
Click
Sizes
0.38 / 0.5 / 0.7 mm
0.38 / 0.5 / 0.7 / 1.0 mm
0.3 / 0.4 / 0.5 / 0.7 / 1.0 mm
Body
Frosted polypropylene
Clear plastic, rubber grip
Plastic, movable binder clip
Where to buy
MUJI stores and muji.us
Most US stores
Most US stores
Price band
$
$
$
Our best gel pens roundup picks one gel pen per job if you’re still choosing.
Is MUJI’s smooth gel pen the same pen?
No. MUJI Japan’s current knock pen is a newer line, さらさら描けるゲルインキボールペン (“smooth-writing gel ink ballpoint”), in 0.3 and 0.5 mm. MUJI Japan lists it at ¥120 (about US$0.80), with a polycarbonate body and pigment gel ink, made in Japan. MUJI USA sells it as the Smooth Gel Ink Ballpoint Knock Pen.
On October 21, 2026, MUJI Japan’s online store linked the cap-type pen from its refillable-pen page, but the product pages we tried no longer opened, and its 0.38 mm gel refill was marked down and out of stock online. In the US, MUJI USA still lists the cap type in all three sizes. Check your local MUJI before stocking up on refills.
Where is the MUJI gel pen made?
In Japan: MUJI USA lists Japan as the country of origin, and MUJI Japan lists Japan for the refill. MUJI doesn’t say which factory makes it.
The pen fits neatly in a MUJI acrylic pen stand, and pairs well with MUJI’s own paper. For a cheaper multipack of 0.7 mm retractable gel pens, the Writech Nebula is a popular Amazon-first alternative.
How much does a MUJI gel pen cost?
It’s in our $ price band, under $5 per pen. MUJI USA sells single pens and 10-pen sets, which work out cheaper per pen; refills are sold singly. The 140 mm pen fits MUJI’s slim Aluminum Pen Case, which is about 173 mm long inside.
On October 22, 2026, MUJI USA’s single 0.38 mm pen cost about 3.2 times MUJI Japan’s list price, the widest maker-to-maker gap in our US vs Japan price comparison.
Frequently asked questions
What sizes does the MUJI gel pen come in?
MUJI USA sells the cap-type gel pen in 0.38 mm, 0.5 mm and 0.7 mm. The 0.38 and 0.5 mm come in 10 colors each; the 0.7 mm in black, blue, red and blue black.
Are MUJI gel pen refills interchangeable between cap and knock pens?
Yes. MUJI USA says its 0.38 mm gel refill fits both the knock-type and cap-type bodies, and MUJI Japan says every color and size of its refills fits either body.
Where are MUJI gel pens made?
In Japan, according to MUJI. MUJI USA lists Japan as the country of origin for the cap-type pen, and MUJI Japan lists Japan for the refill.
How long is the MUJI gel pen?
MUJI USA lists it at 5.5 in (14 cm) with the cap on. MUJI Japan lists the refill inside at about 110 mm long and 6 mm across.
Is MUJI gel ink waterproof?
MUJI doesn't make that claim. MUJI Japan lists the refill's ink as pigment gel ink (顔料), which is usually more water-resistant than dye ink, but we haven't tested it.
Does the MUJI gel pen bleed through paper?
MUJI USA says the water-based ink writes smoothly without bleeding through paper. That's the maker's claim; heavy ink on thin paper can still show through, especially at 0.7 mm.
Is the MUJI gel pen the same as the Pilot G2?
No. The MUJI pen is a capped gel pen with a frosted body sold by MUJI; the Pilot G2 is a retractable gel pen from Pilot with its own refills. Both are Japanese gel pens in the same $ price band.
What is the MUJI smooth gel ink pen?
It's a newer knock-type line that MUJI Japan calls さらさら描けるゲルインキボールペン (smooth-writing gel ink ballpoint), in 0.3 and 0.5 mm, with a polycarbonate body. MUJI USA sells it as the Smooth Gel Ink Ballpoint Knock Pen.
