Provided is a walking assist apparatus comprising a safety device for mitigating the impact of falling. A walking assist apparatus (100) comprises a thigh link (20) and lower leg link (30) fitted to a user, and comprises a motor (26) and controller (12). The lower leg link (30) is connected to the thigh link (20). The controller (12) controls the motor (26) so as to apply torque to the lower leg link (30). The walking assist apparatus further comprises a unidirectional damper (40) for generating resistance force against the rotation of the lower leg link (30) in the knee flexion direction, and for not generating resistance force against the rotation of the lower leg link (30) in the knee extension direction. The controller (12) engages the unidirectional damper (40) while controlling the motor (26) so as to apply, to the lower leg link (30), torque in the knee extension direction, and releases the unidirectional damper (40) while controlling the motor (26) so as to apply, to the lower leg link (30), torque in the knee flexion direction.