An image forming apparatus comprising: a cylindrical image bearing member including a cylindrical support and an organic photosensitive layer (441, 442) provided on the cylindrical support; a developing member configured to supply a developer to the image bearing member for developing a latent image formed on a peripheral surface of the image bearing member; and a cleaning member configured to clean the peripheral surface in contact with the peripheral surface of the image bearing member, characterized in that a plurality of grooves extend in a circumferential direction on the peripheral surface of the image bearing member, and have a width in a generatrix direction of the peripheral surface within a range of at least 0.5 μm and not more than 40 μm, and are formed to be side by side in the generatrix direction; the number of the grooves is at least 20 and not more than 1000 per a width of 1000 μm in the generatrix direction of the peripheral surface of the image bearing member; and an average depth (Rvk) of a valley of a projection under a core section of a roughness curve of the peripheral surface of the image bearing member is 0.08 μm or less, when measured according to the description, an average height (Rpk) of a ridge of the projection above the core section of the roughness curve of the peripheral surface of the image bearing member is not more than 0.02 μm, when measured according to the description, and a sum of the average height (Rpk) of the ridge of the projection above the core section of the roughness curve of the peripheral surface of the image bearing member, a height (Rk) of a core portion forming a center of the roughness curve of the peripheral surface of the image bearing member, and the average depth (Rvk) of the valley of the projection under the core section of the roughness curve of the peripheral surface of the image bearing member is 0.24 μm or less, when measured according to the description. a cylindrical image bearing member including a cylindrical support and an organic photosensitive layer (441, 442) provided on the cylindrical support; a developing member configured to supply a developer to the image bearing member for developing a latent image formed on a peripheral surface of the image bearing member; and a cleaning member configured to clean the peripheral surface in contact with the peripheral surface of the image bearing member, characterized in that a plurality of grooves extend in a circumferential direction on the peripheral surface of the image bearing member, and have a width in a generatrix direction of the peripheral surface within a range of at least 0.5 μm and not more than 40 μm, and are formed to be side by side in the generatrix direction; the number of the grooves is at least 20 and not more than 1000 per a width of 1000 μm in the generatrix direction of the peripheral surface of the image bearing member; and an average depth (Rvk) of a valley of a projection under a core section of a roughness curve of the peripheral surface of the image bearing member is 0.08 μm or less, when measured according to the description, an average height (Rpk) of a ridge of the projection above the core section of the roughness curve of the peripheral surface of the image bearing member is not more than 0.02 μm, when measured according to the description, and a sum of the average height (Rpk) of the ridge of the projection above the core section of the roughness curve of the peripheral surface of the image bearing member, a height (Rk) of a core portion forming a center of the roughness curve of the peripheral surface of the image bearing member, and the average depth (Rvk) of the valley of the projection under the core section of the roughness curve of the peripheral surface of the image bearing member is 0.24 μm or less, when measured according to the description.