An image forming apparatus includes a developer bearing member, a developing bias application unit, a developer supply member, and a supply bias application unit that applies a supply bias to the developer supply member. In a predetermined period before a start of image formation during an image forming operation for an image formed on one recording material, the supply bias application unit applies a supply bias of which the magnitude of an absolute value is smaller than that of a developing bias, to the developer supply member. In a period between the start of image formation and an end of image formation during the image forming operation, the supply bias application unit applies a supply bias to the developer supply member so that a difference in the magnitude of the absolute value from the supply bias in the predetermined period before the start of image formation increases gradually.