Former Moji Mitsui Club, Heritage building in Mojikō Retro, Japan.

The Former Moji Mitsui Club is a half-timbered building with European styling, featuring white walls and carefully carved wooden beams throughout its structure. The building spans multiple floors with various rooms, including the Einstein Memorial Room where the renowned physicist stayed in 1922.

Built in 1921 as the social club of the Mitsui Bussan Moji branch, the club comprised a Western-style main building for receiving guests and a connected Japanese-style annex and warehouse. In 1949 it passed to the Japanese National Railways and was used as the "Montetsu Kaikan" guesthouse. Ownership went to the JNR Settlement Corporation in 1987 and then to Kitakyushu City free of charge. The main building and annex were designated Important Cultural Properties in 1990; the structure was dismantled that July and rebuilt on its present site by December 1994.

The building's name comes from the Mitsui Bussan Moji branch, which used it as a social club for entertaining guests. Today the ground floor houses the restaurant "Mitsui Club," while the second floor holds the Hayashi Fumiko Reference Room, dedicated to the writer born in Moji-ku's Komorie.

The building stands in the Moji Port Retro district, a one-minute walk from JR Moji-ko Station and two minutes from the Kammon Kisen Moji-ko pier; by car it is about five minutes from the Moji-ko IC. The ground floor holds the restaurant Mitsui Club, while the Einstein Memorial Room and the Hayashi Fumiko reference room are upstairs.

The second-floor room where Albert Einstein stayed for one night in 1922 is kept as the Einstein Memorial Room, displayed with materials from his visit. The building also holds a reference room on the second floor for Fumiko Hayashi, a writer said to have been born in Komonoe, Moji-ku.