A developing device is provided that includes a developer containing case that contains a developer. The developer containing case includes a case main body and a supply roller that is rotatably supported on the case main body. The supply roller has a rotary shaft, a cylindrical roller main body that covers the rotary shaft, and a fixed member that is fixed to at least one of the rotary shaft and the roller main body. A gap is provided between an end surface of the roller main body and an inner surface of the case main body, and the fixed member partially occupies the gap.