To provide an image forming apparatus realizing a low production cost.

Regulation means 100 includes: a fixation member 110 supported by a frame 200 displaceably in a positioning direction; a movable member 120 supported by the fixation member 110 displaceably in the positioning direction; and a pressure member 130 provided between the frame 200 and the movable member 120. The pressure member 130 presses the movable member 120 from one side toward the other side of the positioning direction, to bring a third contact surface B3 of the movable member 120 into contact with a third contacted surface A3 of light exposure means 39, bring a second contact surface B2 of the fixation member 110 into contact with a second contacted surface A2 of the light exposure means 39, and bring a first contact surface B1 of the fixation member 110 into contact with a contacted surface A1 of the frame 200 when the light exposure means 39 is in a close position, on the other hand, to bring a forth contact surface B4 of the movable member 120 into contact with a forth contacted surface A4 of the fixation member 110, and bring the first contact surface B1 into contact with the first contacted surface A1 when the light exposure means 39 is in a separation position.