We developed a walking assist machine, which machine used a spatial parallel link mechanism for the elderly or workers. The flat steps of the assist machine move in parallel with the ground and can support the legs of a person including the soles. The machine was equipped various sensors, could turn around during walking and walk in a slope or stairs. Furthermore, the machine was mounted self-contained control system used a SH-4 microcomputer and Lithium-ion batteries. As a result, the equipped person can walk without limitation of the area where the machine can be used. The EMG while the equipped person walked on the stairs was measured, and the ratio of IEMG between the data while wearing and without wearing the machine, and MVC were calculated. As a result, the machine was effective to use during walking on the stairs for the lower leg (crural leg) of the equipped person.