An elastic unit includes a transatory unit including a first elastic support member, a second elastic support member and not-shown four round bar-shaped elastic bodies made of rubber. A rotation urging unit is composed of a Neidhart spring including an outer frame, a shaft, a rotary member, and four rubber rods. The rotary member is in a state where it is rotated at 10° counterclockwise from an initial state. Therefore, the rubber rod deforms upon reception of rolling friction from the outer frame and the rotary member, and the rotation urging unit gives the handle portion the urging power by which the handle portion is rotated so that one end of the handle portion is spaced away from a gear housing 31 in the direction of the handle portion.