An image forming apparatus comprising: a photoconductive member (1a,1b 1c,1d) configured to bear a toner image; a movable endless intermediate transfer member (110, 210, 310) in contact with the photoconductive member, the toner image born by the photoconductive member being primarily transferred to the intermediate transfer member (110, 210, 310); and a developing unit (4a, 4b, 4c, 4d) configured to develop the toner image on the photoconductive member, the developing unit capable of collecting residual toner remaining on the photoconductive member after the toner image is primarily transferred from the photoconductive member to the intermediate transfer member (110, 210, 310), wherein the intermediate transfer member (110, 210, 310) has a plurality of grooves (210a, 310a) formed on a surface in contact with the photoconductive member, and the grooves continuously extend in a movement direction of the intermediate transfer member (110, 210, 310) and are arranged in a width direction crossing the movement direction of the intermediate transfer member (110, 210, 310), and wherein the grooves are diagonally formed at an angle θ to the movement direction and satisfies the following Expression: I ≤ L × tan θ where I represents an interval between adjacent ones of the grooves in the width direction, and L represents a circumferential length of the intermediate transfer member (110, 210, 310) in the movement direction, characterized in that the intermediate transfer member (110, 210) has convex portions formed on either side of one of the grooves in the width direction, and the convex portions continuously extend in the movement direction of the intermediate transfer member (110, 210). a photoconductive member (1a,1b 1c,1d) configured to bear a toner image; a movable endless intermediate transfer member (110, 210, 310) in contact with the photoconductive member, the toner image born by the photoconductive member being primarily transferred to the intermediate transfer member (110, 210, 310); and a developing unit (4a, 4b, 4c, 4d) configured to develop the toner image on the photoconductive member, the developing unit capable of collecting residual toner remaining on the photoconductive member after the toner image is primarily transferred from the photoconductive member to the intermediate transfer member (110, 210, 310), wherein the intermediate transfer member (110, 210, 310) has a plurality of grooves (210a, 310a) formed on a surface in contact with the photoconductive member, and the grooves continuously extend in a movement direction of the intermediate transfer member (110, 210, 310) and are arranged in a width direction crossing the movement direction of the intermediate transfer member (110, 210, 310), and wherein the grooves are diagonally formed at an angle θ to the movement direction and satisfies the following Expression: I ≤ L × tan θ where I represents an interval between adjacent ones of the grooves in the width direction, and L represents a circumferential length of the intermediate transfer member (110, 210, 310) in the movement direction, characterized in that the intermediate transfer member (110, 210) has convex portions formed on either side of one of the grooves in the width direction, and the convex portions continuously extend in the movement direction of the intermediate transfer member (110, 210).