A gear made of a resin including substantially annular toothed portion formed at a radially outer location, a shaft-supporting section formed at a radially inner location around a rotational center of the toothed portion, and a web connecting the shaft-supporting section and the toothed portion to each other. A circumferential rib is formed on the web concentrically with the toothed portion, and diametrical ribs are also formed on the web radiately to connect the circumferential rib and the shaft-supporting section to each other in a radial direction.