To reduce the dead body of a leg body movement assist device to be worn on a person applied to the person and to allow the person to perform leg body exercise with a feeling of non-wearing the leg body movement assist device as much as possible.

When the person A wearing the leg body movement assist device 1 performs the leg body exercise, if the same exercise as the leg body exercise is performed by the person A detaching the assist device 1, this method estimates a person side joint moment to be generated in the respective joints of the leg bodies of the person A and, if the assist device 1 singularly performs the same exercise as the leg body exercise, estimates a device side joint moment to be generated in joint portions 4, 6 and 10 of the respective leg bodies of the assist device 1. The estimate of the device side joint moment is defined as the reference torque of the torque generation means 18, 19 and 20 and a torque obtained by adding a torque according to the estimate of the person side joint moment to the reference torque is generated in the torque generation means 18, 19 and 20.