A shoulder brace includes a shoulder cuff that can be worn to cover the shoulder of a user, an upper arm cuff that can be worn to cover the elbow joint of the user, a belt that can secure the shoulder cuff to the shoulder of the user, and an actuator that is the McKibben artificial muscle which can optionally expand and contract in entire length. The actuator contains a main actuator to link the vicinity of the acromion on the shoulder cuff and a side face of the upper arm cuff across the shoulder joint, an anterior auxiliary actuator to link a front face of the shoulder cuff and a front face of the upper arm cuff across the shoulder joint, and a posterior auxiliary actuator to link a back face of the shoulder cuff and a back face of the upper arm cuff across the shoulder joint.