To reduce noise and to prevent gear skipping.

A gear mechanism is provided with: a gear member 65 with a small diameter section 111 and a large diameter section 112 on which small diameter gears 63 and large diameter gears 64 are respectively formed on the outer peripheries, and are integrally formed with a synthetic resin material with the small diameter section formed to be hollow in a state of being cylindrically protruded from a side surface of the large diameter section; and a restricting member 113 with a restricting section 121 provided inside the small diameter section for restricting deflection of the small diameter section. The outer periphery surface of the restricting section is formed to have a smaller diameter than the inner periphery surface of the small diameter section of the gear member. A gap is provided between the outer periphery surface of the restricting section and the inner periphery surface of the small diameter section, and has a size for limiting the deflection in the small diameter section to be within a range with no occurrence of gear skipping, while allowing the deflection in the small diameter section required for reduction of noise.