An opening and closing device for moving a movable member which includes a drive gear connected to a power source, a driven gear geared with the drive gear, an immovable portion supporting the drive gear and the driven gear, and a dynamic transmission mechanism connected to the driven gear so that the driven gear and the dynamic transmission mechanism rotate together as a unit. The dynamic transmission mechanism transmits a drive force of the power source from the driven gear to the movable member. A direction of a rotational force affecting the driven gear via the dynamic transmission mechanism in accordance with a state of the movable member fluctuates. The opening and closing device further includes a friction member located at least at one position between relatively movable facing surfaces of the immovable portion, the drive gear, the driven gear, and the dynamic power transmission mechanism.