Ichijinsha (Japanese: 株式会社一迅社, Hepburn: Kabushiki-gaisha Ichijinsha) is a Japanese publishing company focused on manga-related publication, including magazines and books.

The company was first established in August 1992 as a limited company under the name Studio DNA whose main purpose was to edit shōnen manga. In January 1998, Studio DNA became a public company and moved from merely editing to now being a publishing company. In December 2001, a publishing company was formed named Issaisha which started the shōjo manga magazine Monthly Comic Zero Sum. In March 2005, Studio DNA and Issaisha merged into the current Ichijinsha company. In October 2016, Ichijinsha was acquired by Kodansha and became its wholly owned subsidiary.