A retractable seat device includes a seat body having first and second ends rotatably connected to rear and front legs, respectively, first and second arms, and a link. When the first arm is rotated in a second direction, the rear leg and the front leg connected to the rear leg with the link are unfolded, a rear lock mechanism provided on the rear leg becomes engaged with a first striker provided on the vehicle floor, and then a front lock mechanism provided on the front leg becomes engaged with a second striker provided on the vehicle floor, so that the seat body is supported on the vehicle floor by the rear leg and the front leg. The rear lock mechanism has an interlock structure including a ratchet and a pawl, and the front lock mechanism has a hook lock structure including a hook.