Mitsui Takatoshi

was a Japanese businessman who founded the Mitsui family of merchants and industrialists that later emerged as the Mitsui Group, a powerful zaibatsu (business conglomerate). The Mitsui family was a branch of Fujiwara Hok-ke.

He moved to Edo at 14 years of age, following his eldest brother Toshitsugu who had extended the family business by opening a kimono store (呉服屋, gofukuya) there in 1627. Takatoshi in a little over a decade rose to be manager of his brother's shop.

In 1649, his elder brother Shigetoshi died at the age of 36, and he returned to Matsusaka to look after his aging mother, remaining there for two decades. There, he married Nakagawa Kane, the eldest daughter of the Nakagawa merchant family; the two had ten sons and five daughters. He returned to Edo on his elder brother Toshigutsu's death in 1673. He then established the Echigoya Drapery in Nihonbashi the following year, which was to become, later, the head company of the famous Mitsukoshi retail shopping chain. He also set up a material supplies store in Kyoto at this time. In contrast to most drapery merchants, who catered to feudal houses and wealthy merchants, trading on credit with no fixed prices, Takatoshi introduced an innovatory system of cash based purchase based on fixed prices for wares and targeted consumers in the emerging middle class.

He subsequently started a money exchange in 1683, with a new system for inter-city loans. He extended the family business by opening an outlet in Osaka, and was appointed official purveyor of dry goods to the Tokugawa shogunate in 1687. He also relocated, in 1686, the headquarters of the family business from Matsusaka to Kyoto. He died at the age of 73.

Mitsui had six sons.