A latch mechanism includes a latch and a rotation shaft supporting part. The latch is rotatable around a rotation shaft between a housing position and a lock position, and fixes a first unit and a second unit in a closed state at the lock position. The rotation shaft supporting part rotatably supports the rotation shaft. The latch has a first ring-shaped part disposed coaxially with the rotation shaft. The rotation shaft supporting part has a second ring-shaped part disposed coaxially with the rotation shaft. Heights of the first ring-shaped part and the second ring-shaped part are set such that an area of abutment between the first ring-shaped part and the second ring-shaped part increases as the latch rotates from the lock position to the housing position.