In this paper, we present a system design about a gait training device for monoplegia patients and aged people. In a conventional gait training program, the monoplegia patient takes a step leaning on the parallel guide bar or helped by a therapist's arm support. But this method often does not give satisfactory result since the method fails to correct the irregular posture of the patient. The new training device has been in need for gait disorder patients, monoplegia patients and aged people. The gait training device for the patients is divided into four main units, gait phase detecting unit, lower panel controlling unit, lower limb pulling and releasing unit and additional supplementary unit for safety of the patients. The training device to be presented exhibits stableness in its operation and it may improve the effect of gait rehabilitation training compared to the conventional gait training method.