An object is to provide an attitude control system that can suppress an understeering characteristic when a vehicle such as an automobile travels in a medium-speed or low-speed range. A vehicle (1) drives front wheels (11A, 11B), and controls steering angles of the front wheels (11A, 11B) and steering angles of rear wheels (21A, 21B). In an attitude control system (30) to be mounted on the vehicle(1), a control amount detecting unit (31) detects an operation amount (P) of an accelerator pedal (15) operated by a driver of the vehicle (1). A driving force estimating unit (32) estimates a driving force generated on the front wheels (11A, 11B) based on the operation amount (P) of the accelerator pedal (15). A rear-wheel steering angle determining unit (33) determines a rear-wheel steering angle instruction value ([delta]R*) for controlling steering angles ([delta]R) of the rear wheels (21A, 21B) based on an estimated front-wheel driving force (FXF) that is the driving force estimated by the driving force estimating unit (32).