A light-orientation adjusting unit for use with a light-receiving member, comprising: an optical unit to pass a light beam toward the light-receiving member, the optical unit being movable to change a posture of the optical unit; an inclination control unit (56, 58) to control the posture of the optical unit to adjust an inclination of a scanning line to be formed on the light-receiving member by the light beam; a first biasing member configured to contact a first end of an upper face of the optical unit to bias against movement of the optical unit, the first biasing member being elastically deformable over a first range; the first biasing member being included as part of a regulating member (61 b) that is configured to limit the movement of the first end of the optical unit to within said first range and so prevent a plastic deformation of the first biasing member, the first regulating member having a greater rigidity than the first biasing member; and a second biasing member configured to contact a second end of the upper face of the optical unit to bias against movement of the optical unit, the second biasing member being elastically deformable over a second range; the second biasing member being included as part of a second regulating member that is configured to limit the movement of the second end of the optical unit to within said second range and so prevent a plastic deformation of the second biasing member, the second regulating member having a greater rigidity than the second biasing member; wherein the first regulating member is fixed at a given position while securing a first clearance with the optical unit that is no greater than the first range, the first regulating member being configured to contact the first end of the upper face of the optical unit when the optical unit is moved for a distance of the first clearance, and the second regulating member is fixed at a given position while securing a second clearance with the optical unit that is no greater than the second range, the second regulating member being configured to contact the second end of the upper face of the optical unit when the optical unit is moved for a distance of the second clearance. an optical unit to pass a light beam toward the light-receiving member, the optical unit being movable to change a posture of the optical unit; an inclination control unit (56, 58) to control the posture of the optical unit to adjust an inclination of a scanning line to be formed on the light-receiving member by the light beam; a first biasing member configured to contact a first end of an upper face of the optical unit to bias against movement of the optical unit, the first biasing member being elastically deformable over a first range; the first biasing member being included as part of a regulating member (61 b) that is configured to limit the movement of the first end of the optical unit to within said first range and so prevent a plastic deformation of the first biasing member, the first regulating member having a greater rigidity than the first biasing member; and a second biasing member configured to contact a second end of the upper face of the optical unit to bias against movement of the optical unit, the second biasing member being elastically deformable over a second range; the second biasing member being included as part of a second regulating member that is configured to limit the movement of the second end of the optical unit to within said second range and so prevent a plastic deformation of the second biasing member, the second regulating member having a greater rigidity than the second biasing member; wherein the first regulating member is fixed at a given position while securing a first clearance with the optical unit that is no greater than the first range, the first regulating member being configured to contact the first end of the upper face of the optical unit when the optical unit is moved for a distance of the first clearance, and the second regulating member is fixed at a given position while securing a second clearance with the optical unit that is no greater than the second range, the second regulating member being configured to contact the second end of the upper face of the optical unit when the optical unit is moved for a distance of the second clearance.