The invention discloses a light source drive circuit driving a light source, an optical scanning apparatus, a semiconductor drive circuit and an image forming apparatus. The light source drive circuit includes a drive current generating unit which generates a drive current, the driving current including a predetermined current for obtaining a predetermined light amount from the light source and first and second overshoot currents which are applied to the predetermined current in synchronization thereto; and a control unit which sets, to the drive current generating unit, a value of the first overshoot current to a fixed value, and a value of the second overshoot current in accordance with a light amount output from the light source.