A development device includes a developer carrier and a developer supply belt. The developer carrier, disposed in contact with an image carrier carrying an electrostatic latent image, carries developer to be charged with a prescribed polarity and develops the electrostatic latent image by application of development voltage. The developer supply belt includes a first roller, a second roller, and a belt. The belt is tightly stretched by the first roller and the second roller, and is disposed in contact with the developer carrier from a contact beginning portion to a contact finishing portion. A potential difference between the development voltage and the voltage of the contact finishing portion is arranged to be zero (0) V or above and 600 V or below.