An image forming apparatus includes an image bearing member on which a toner image is to be formed; a transfer device for transferring the toner image carried on the image bearing member; and a rotationally movable endless transfer belt onto which the toner image is to be transferred or on which a transfer material onto which the toner image is to be transferred is to be conveyed. The transfer device includes a sheet member contacted to an inner peripheral surface of the transfer belt while being supported by a supporting member at an end thereof and includes an urging member for urging the sheet member against the transfer belt in contact to the sheet member. The urging member includes a projected portion projected toward the transfer belt at its downstream end portion more than at its upstream end portion with respect to a movement direction of the transfer belt.