An elastic actuator includes a gear transmitting a rotational force; a mounting recess formed in a first side of the gear; a plurality of elastic wedges received in the mounting recess at positions that are spaced apart from each other in a circumferential direction of the mounting recess, each elastic wedge including a non-metal elastic material; a through-hole penetrating an elastic wedge among the plurality of elastic wedges; an output body configured to cover the first side of the gear; and at least one insertion bar protruding from a first side of the output body toward the first side of the gear and configured to be inserted into the through-hole. The elastic actuator further includes a shaft coupled to the output body and penetrating the gear, a protrusion having an inner space through which the shaft passes being formed to extend from the mounting recess toward the output body.