An actuator unit of the present invention includes upper and lower frames respectively connectable to a thigh frame and a lower leg frame, an actuator-side rotational connecting part connecting both frames in a rotatable manner around a pivot axis, a driver producing driving force for rotating the lower frame around the pivot axis, upper and lower connecting bodies respectively connecting the upper frame to the thigh frame and the lower frame to the lower leg frame, and an intermediate connecting body connecting the vicinity of the actuator-side rotational connecting part to the vicinity of a brace-side rotational connecting part, the intermediate connecting body having a ball stud and an accommodation depression respectively provided on one and the other of the knee-ankle-foot orthosis and the actuator unit.
