A gait motion assisting apparatus of the present invention includes an actuator unit controlling driver so that assisting force calculated by applying gait motion timing based on detected thigh phase angle to output pattern saved data is imparted to lower leg, and a terminal device capable of wireless-communicating with control device of the actuator unit. The terminal device can receive assisting force setting value including assisting force imparting period during gait cycle and create, based on the assisting force setting value, output pattern setting data indicating a relationship between the gait motion timing and a size of assisting force to be imparted to the lower leg. The control device is configured to overwrite-save the output pattern setting data received from the terminal device as the output pattern saved data.