Provided is a vehicle seat flip-up mechanism that may be stably fixed to a vehicle body floor and may stably support a load of an occupant. In a vehicle seat flip-up mechanism that is provided to switch a posture of a seat cushion between a normal sitting posture and a stowed posture where the seat cushion is stowed while being inclined forward, the vehicle seat flip-up mechanism includes: links (121) that extend in the front to back direction while being separated from each other in the seat width direction; a mounting bracket (124) that is attached to the ends of the links (121) and supports a seat cushion; a connection member (123) that is installed in the mounting bracket (124); a support mechanism (125) that rotatably supports the links (121); and mounting plates (112, 113) that are disposed below the support mechanism (125) and are locked to the vehicle body floor, in which the mounting plate (112) extends rearward relative to the link (121).