An apparatus includes: a cam that has two cam members disposed facing each other and produces thrust in an axis direction; an attracting member that creates friction force by attracting the cam members into contact with the attracting member by magnetic attraction force; an attracted member that is attached to one cam member of the two so as to rotate integrally together with the one cam member and be relatively movable in the axis direction, and that is attracted by the attracting member into contact with the attracting member so that the friction force is produced; a first return spring that exerts elastic force on the attracted member so as to move the attracted member away from the attracting member against the magnetic attractive force; and a second return spring that exerts elastic force on the one cam member.