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Ichitaro 2006 screenshot.jpg
Developer(s) JustSystems
Stable release
Ichitaro 2016 / 5 February 2016
Operating system Microsoft Windows, Linux
Type Word processor
License Proprietary
Website www.ichitaro.com

Ichitaro (一太郎, ichitarō) is a Japanese word processor produced by JustSystems, a Japanese software company. Ichitaro occupies the second share in Japanese word-processing software, behind Microsoft Word. It is one of the main products of the company. Its proprietary file extension is ".JTD". ATOK, an IME developed by JustSystems, is bundled with Ichitaro.


The company developed the Japanese word processor JS-WORD for the PC-100 in 1983. In the following year, jX-WORD for the IBM JX was released and in the following year, jX-WORD Taro was released for PC-9801. The same year, Ichitaro was released as its definite successor.

In the DOS era, Ichitaro had a considerable market share along with other rivals such as Matsu by Kanri Kougaku Kenkyujyo. However, as Windows became dominant, the market was largely taken over by Microsoft Word.[1] Some versions of Ichitaro were ported to the Macintosh and to OS/2. In May 2003, the release of a Linux version was announced.

Compact versions, "Ichitaro dash" and "Ichitaro lite" are produced for laptop PCs. As office suite, "Just home" is also available. "Ichitaro smile" is targeted at elementary school students and "Ichitaro jump" at middle and high school students.

On 1 February 2005, sales and production of the software were frozen pending an appeal by the company against a ruling of the Tokyo District Court which states that there is a breach of a patent owned by Matsushita Electric Industrial Co., Ltd.[2]

However, on 30 September 2005, Intellectual Property High Court of Japan, which was newly formed in April 2005, has granted JustSystems’ appeal. Because this judgement became a final decision in October 2005, the original decision sentenced by the Tokyo District Court was overturned.[3]


In 2013, Symantec revealed that Ichitaro had the potential to be targeted by trojan horse programs.[4] A gang of Chinese hackers was widely blamed for the incident.[5]

See also[edit]

Further reading[edit]


  1. ^ The Yomiuri Shimbun, pp.9 Tokyo morning edition, 8 April 1998.
  2. ^ The Yomiuri Shimbun, pp.1 Tokyo morning edition, 2 February 2005.
  3. ^ The decision of case 2005 (Ne) 10040, Intellectual Property High Court of Japan - 30 September 2005
  4. ^ Symantec: "Yet Another Zero-Day: Japan Hit with Ichitaro Vulnerability", 14 November 2013. Accessed 3 March 2014
  5. ^ "New York Times hackers linked to Japan Ichitaro attacks", The Register, 18 November 2013. Accessed 3 March 2014

External links[edit]