A rotating device includes a shaft member, a counterpart member, a bearing, and a retaining member. The counterpart member includes a shaft insertion portion into which the shaft member is inserted. The bearing is disposed in the shaft insertion portion and interposed between the counterpart member and the shaft member. The bearing causes the counterpart member and the shaft member to be rotatable relative to each other. The retaining member is disposed on an end portion of the shaft member on one side in an axial direction of the shaft member. The counterpart member includes an opposing portion closer to the end portion of the shaft member on the one side in the axial direction than the bearing. The opposing portion faces the retaining member in the axial direction.