A developing device is provided with which the increase in torque of a supply roller, unevenness of image density, and wear to the supply roller caused by the formation of an aggregated block of toner in the gap between the supply roller and the opposing side wall of a supply developer holding chamber can be suppressed. This developing device comprises a developing roller for developing an electrostatic latent image supported on a photoconductive member, a supply developer holding chamber for holding toner to be supplied to the developing roller, a supply roller for supplying the toner supported on the peripheral face thereof to the developing roller, a hopper that is disposed above the supply developer holding chamber and used to hold toner for replenishing the supply developer holding chamber, and a communication opening for allowing the hopper to communicate with the supply agent holding chamber, wherein a canopy member is provided directly above the gap to impede the advance of the toner on the supply roller into the gap between the supply roller and the opposing side wall of the supply developer holding chamber.