A seat apparatus for an automobile comprises: a seat cushion which is movable between a sitting position and a position for getting into and getting out of the automobile, the position is remote forward or rearward from the sitting position; a guide device for guiding the seat cushion between the sitting position and the position for getting into and getting out of the automobile; a backrest which is rotatably connected to the seat cushion via a hinge structure; a locking mechanism which causes the seat cushion to engage and disengage with the guide device, and a lock switching device is provided on the seat cushion and the backrest. The lock switching device releases an engagement between the seat cushion and the guide device performed by the lock mechanism and when the backrest is inclined forward to the seat cushion at a predetermined angle, and engages the seat cushion and the guide device with each other when the backrest is further inclined forward so as to be substantially horizontal.