Est. 2026 · Price: FreeEditor-at-large: The Hedgehog

Stationery Times

Brand: MUJI

MUJI Oil Ink Polycarbonate Ballpoint Pen 0.7 mm

Compiled from 3 sources; we haven't tested this product ourselves yet. How we research

Quick answer

The MUJI Oil Ink Polycarbonate Ballpoint Pen is a simple 0.7 mm ballpoint with a polycarbonate body. MUJI USA lists it at 14.0 cm (5.5 in) long and 1.5 cm across, says the oil ink withstands a light wash, sells it in black and red, and gives Japan as the origin.

On this page10 sections
MUJI Oil Ink Polycarbonate Ballpoint Pen 0.7 mm drawn to scale at 14.0 cm long and 1.5 cm across with a pocket clip
The pen at MUJI USA's listed 14.0 cm by 1.5 cm (1 mm = 6.25 px). Original illustration made for this guide. © Stationery Times.

Product facts

Product
MUJI Oil Ink Polycarbonate Ballpoint Pen 0.7 mm
Brand
MUJI
Brand origin
Japan
Made in
Japan*
Material
Polycarbonate and elastomer (per MUJI USA)
Good for
Price range
$under $5 per pen (multi-packs divided by the count)
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Notes on these facts
  • Made by Ryohin Keikaku Co., Ltd.. Made in Japan: MUJI USA's product details give "Country/Region of Origin: Japan". Source. Price: example listing.
  • How we test and disclose samples: How we test stationery.
  • Price bands are typical US retail, checked October 2026.

Key takeaways

  • MUJI USA lists the pen at 14.0 cm (5.5 in) long and 1.5 cm (0.6 in) across, with a 0.7 mm tip.
  • The body is polycarbonate with an elastomer part; the ink is oil-based.
  • MUJI says the oil ink can withstand a light wash and suits multi-media sketches; that is a maker claim, not our test.
  • Two colors in the US: black and red, and MUJI sells matching 0.7 mm refills.
  • MUJI USA gives Japan as the origin, and each pen is in our $ band (under $5).

What is the MUJI Oil Ink Polycarbonate Ballpoint Pen?

It’s a plain ballpoint with a 0.7 mm tip and an oil-based ink, sold by MUJI in black and red. MUJI USA describes it as a simple pen for everyday use. MUJI is the brand of Ryohin Keikaku, the Japanese retailer.

The barrel is unusually thick for a pen this plain: 1.5 cm across, per MUJI USA. That helps people who find slim pens tiring.

MUJI oil ink ballpoint specs

Spec Value
Maker MUJI (Ryohin Keikaku Co., Ltd.), Japan
Type Ballpoint pen, refillable
Length 14.0 cm (5.5 in)
Diameter 1.5 cm (0.6 in)
Tip 0.7 mm (about 0.03 in)
Ink Oil-based
Materials Polycarbonate, elastomer
Colors (US) Black, red
Barcode (black) 4548718444434
Made in Japan (MUJI USA)

MUJI USA gives no weight, and its listing doesn’t say how the pen opens or closes, so the clip and button in our drawing are drawn by eye.

Who is the MUJI oil ink ballpoint for?

It suits people who want a plain, cheap everyday ballpoint with a thick barrel.

  • Everyday writing: MUJI USA calls it a simple pen for everyday use, in our $ band, with 0.7 mm refills sold separately.

Skip it if you want a fine line: 0.7 mm is the widest ball MUJI sells in its smooth oil ink range.

Bars at 20 times scale showing 0.38, 0.5 and 0.7 mm nominal ball sizes
This pen's 0.7 mm ball against the 0.38 and 0.5 mm sizes of MUJI's smooth oil ink pens (nominal, at 20×). Original illustration made for this guide. © Stationery Times.

Does the oil ink survive water?

MUJI USA says the oil-based ink can withstand a light wash and suits multi-media sketches. That is a claim about washing over a drawn line, not about soaking.

Oil-based ballpoint ink usually sits on the paper rather than soaking in, which is why the maker can say this. We haven’t tested it, and the hands-on slot below is where our test will go.

How do the refills work?

MUJI USA sells a 0.7 mm refill for its polycarbonate ballpoint pens in colors such as blue and red. It also lists the pen in black and red, so a blue refill gives you a third color in the same body. Check the refill listing for the exact color you want.

How does it compare with MUJI’s other ballpoints?

It’s the thickest and the widest-lined; the smooth oil ink pen is slimmer with a grip and three ball sizes.

Oil Ink Polycarbonate Smooth Oil Ink
Length 14.0 cm (5.5 in) 14.1 cm (5.6 in)
Ball sizes 0.7 mm 0.38 / 0.5 / 0.7 mm
Ink Oil-based Oil-based, quick drying
Made in Japan Japan

For the gel alternatives see MUJI’s gel ink pen and the roundup of best ballpoint pens.

Where is it made, and what does it cost?

In Japan: MUJI USA gives Japan as the country or region of origin. Each pen is in our $ band, under $5. MUJI USA sells it as Final Sale, with no refunds or exchanges; we read the page on November 1, 2026, and prices change.

Frequently asked questions

Is the MUJI oil ink ballpoint waterproof?

MUJI USA says the oil-based ink can withstand a light wash. That is not the same as waterproof, and we haven't tested it.

How thick is the MUJI polycarbonate ballpoint pen?

MUJI USA lists a diameter of 1.5 cm (0.6 in) and a length of 14.0 cm (5.5 in), which makes it a fairly fat barrel.

What colors does the MUJI oil ink ballpoint come in?

MUJI USA lists black and red.

Can you refill the MUJI polycarbonate ballpoint pen?

MUJI USA sells a Refill for Polycarbonate Ballpoint Pen 0.7mm in colors such as blue and red, so the pen is meant to be refilled. We haven't checked every refill color.

Is the MUJI oil ink pen made in Japan?

Yes. MUJI USA lists Japan as the country or region of origin.

Does the MUJI ballpoint have a clip or a cap?

MUJI USA's listing mentions neither. We drew a clip by eye, so check the product photos before you buy.

Can I return a MUJI pen bought online?

MUJI USA marks it Final Sale, with no refunds or exchanges, on its product page as we read it.

Sources (3)

  1. MUJI USA: Oil Ink Polycarbonate Ballpoint Pen 0.7mm (Dia. 1.5 x Length 14.0 cm; tip 0.7 mm; polycarbonate, elastomer; oil-based ink; Japan; black and red; read in full November 1, 2026)
  2. MUJI USA: Oil Ink Polycarbonate Ballpoint Pen 0.7mm - Refill - Blue (listing seen in the stationery collection)
  3. MUJI USA stationery collection (product list, read November 1, 2026)

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