The present invention has an object to provide a seat for vehicles in which a seat cushion flip-up mechanism can be space-saving. In a seat for vehicles which has a flip-up mechanism to shift a seat cushion frame (200) disposed on a base part (5) from a normal seating posture (200-1) to a flipped-up posture (200-2), the flip-up mechanism includes: a support leg part (301) having one end connected to the seat cushion frame (200) rotatably around a first rotation shaft (303) and the other end connected to the base part (5) rotatably around a second rotation shaft (302); a guide part (201a) to be engaged with the one end of the support leg part (301) to guide the one end so as to lift the one end; and a coil spring (305) applying a biasing force so as to have the one end guided by the guide part (201a) and flip up a portion (303) connected with the seat cushion frame (200).