To provide a multi-beam scanner by which an optical device such as a polygon mirror is miniaturized by making the occupancy width of a plurality of light beams emitted by a light source part as narrow as possible in the multi-beam scanner provided with a plurality of array light sources.

A beam spot array line 21 passing through the center points 51 and 52 of beam spots S1 and S2 when an image is formed with two laser beams emitted by one array light source on a photoreceptive drum and a beam spot array line 22 passing through the center points 53 and 54 of beam spots S3 and S4 when an image is formed with two laser beams emitted by the other array light source on the photoreceptive drum, have the interval of one pixel portion and also made in parallel in a sub-scanning direction (the direction of an arrow Y), and also the positions of four laser beams are adjusted so that deviation in the main scanning direction (the direction of an arrow X) of the beam spots S1 and S3 becomes zero.