An image forming apparatus suitable to form image on both sides of a recording sheet and adapted to form an electrostatic latent image on a photosensitive member, to develop the electrostatic latent image on the photosensitive member into a visible image by developer and to transfer the visible image to the recording sheet, the image forming apparatus comprising: a conveying path that includes a first U shape portion at which the recording sheet moving from a recording sheet accommodating unit installed at a lower section of a housing toward one end of the housing turns in a U shape toward the other end of the housing; the conveying path is adapted to convey the recording sheet from the recording sheet accommodating unit via a region corresponding to the photosensitive member and then out of the housing; a registration roller that is disposed at an upstream position of the photosensitive member in the conveying path and is adapted to regulate a tip end of the recording sheet moving toward the photosensitive member; an inverting path that is a path along which the recording sheet returns from a downstream position of the photosensitive member in the conveying path to an upstream position of the registration roller in the conveying path, the inverting path including a second U shape portion joining with the upstream position of the registration roller; a supply roller that supplies the developer to a developing roller; and a developer accommodating unit that accommodates the developer, wherein a lower wall portion of the developer accommodating unit is in a continuous contact with a roller wall portion that is formed along a lower circumference of the supply roller, wherein an upwardly depressed portion is formed with the lower wall portion and the roller wall portion, wherein the conveying path includes a downward slope portion that runs obliquely down from a topmost position of the first U shape portion toward a nipping position of the registration roller; and wherein the topmost position, a joining position in which the inverting path is connected to the conveying path, and the nipping position of the registration roller get lower in a vertical direction in this order, characterized in that the registration roller regulates the tip end of the sheet by keeping on being in a stop state for a predetermined time, and at least a part of the registration roller is placed in the upwardly depressed portion, such that the registration roller is at least partially overlapped with the supply roller when being viewed from a horizontal direction perpendicular to the vertical direction and perpendicular to a rotational axis of the registration roller, the rotational axis of the registration roller being perpendicular to the vertical direction. a conveying path that includes a first U shape portion at which the recording sheet moving from a recording sheet accommodating unit installed at a lower section of a housing toward one end of the housing turns in a U shape toward the other end of the housing; the conveying path is adapted to convey the recording sheet from the recording sheet accommodating unit via a region corresponding to the photosensitive member and then out of the housing; a registration roller that is disposed at an upstream position of the photosensitive member in the conveying path and is adapted to regulate a tip end of the recording sheet moving toward the photosensitive member; an inverting path that is a path along which the recording sheet returns from a downstream position of the photosensitive member in the conveying path to an upstream position of the registration roller in the conveying path, the inverting path including a second U shape portion joining with the upstream position of the registration roller; a supply roller that supplies the developer to a developing roller; and a developer accommodating unit that accommodates the developer, wherein a lower wall portion of the developer accommodating unit is in a continuous contact with a roller wall portion that is formed along a lower circumference of the supply roller, wherein an upwardly depressed portion is formed with the lower wall portion and the roller wall portion, wherein the conveying path includes a downward slope portion that runs obliquely down from a topmost position of the first U shape portion toward a nipping position of the registration roller; and wherein the topmost position, a joining position in which the inverting path is connected to the conveying path, and the nipping position of the registration roller get lower in a vertical direction in this order, characterized in that the registration roller regulates the tip end of the sheet by keeping on being in a stop state for a predetermined time, and at least a part of the registration roller is placed in the upwardly depressed portion, such that the registration roller is at least partially overlapped with the supply roller when being viewed from a horizontal direction perpendicular to the vertical direction and perpendicular to a rotational axis of the registration roller, the rotational axis of the registration roller being perpendicular to the vertical direction.