To obtain a laser scanning optical apparatus, capable of adjusting a plurality of cylindrical lenses with high accuracy in an optical axis direction, and suppressing variation in the beam diameter to the utmost, thereby correcting the beam pitch in a sub scanning direction.

The laser scanning optical apparatus includes: a light source having a plurality of light emitting points; an optical element which makes the beams emitted from the light source parallel light; first and second cylindrical lenses 5, 6 which condense the beams emitted from the optical element on the deflection plane of a polygon mirror in a line form in a main scanning direction Y; a holding member 51 which holds the lenses 5, 6; a base which supports the holding member 51 such that the holding member is slid in the optical axis direction X and turned around the optical axis, and the sliding position and the turning position can be fixed. The holding member 51 has reference planes 51b which are formed as the same plane to which the mounting planes of the lenses 5, 6 perpendicular to the optical axis are abutted, respectively, fixes the position of the first lens 5 on the reference plane 51b and holds the second lens 6 on the reference plane 51b so that the second lens 6 is slid in the optical axis direction X and the position of the second lens can be fixed.