An actuator comprises a motor including a rotation shaft; an output shaft disposed coaxially to the rotation shaft; a rotation shaft side gear rotatable as a unit with the rotation shaft; an output shaft side gear rotatable as a unit with the output shaft; an intermediate gear configuration body that includes a first intermediate gear and a second intermediate gear and that meshes with the rotation shaft side gear and the output shaft side gear; a first bearing supporting an end portion of the intermediate gear configuration body at a side of the first intermediate gear; and a second bearing supporting another end portion of the intermediate gear configuration body at a side of the second intermediate gear; wherein the second intermediate gear is rotatable as a unit with the first intermediate gear and is disposed further to a radial direction outside of the motor than the first intermediate gear.