A lateral pressure mechanism 4 for a motor has a first ring 5 which is fixed to a stator-side member 2 so as to surround a rotary shaft 50; a second ring 6 which is disposed inside the first ring so as to surround the rotary shaft 50, and which is radially movable inside the first ring 5; and a wire spring 7 which is bridged between two engaging portions 11 and 13 of the first ring 5 so that an intermediate part abuts against the outer peripheral surface of the second ring.