Patent ID: 8446448

Claim:
An optical scanning unit comprising: a laser diode holder to which a laser diode is fixed; and a holding portion for holding the laser diode holder, in which the laser diode holder is fixed to the holding portion by applying an adhesive agent to couple an outer circumferential surface of the laser diode holder and a wall surface of an opening provided in the holding portion, wherein each of the outer circumferential surface of the laser diode holder and the wall surface of the opening has a recess at a portion to which the adhesive agent is applied, at least one of the recess of the outer circumferential surface of the laser diode holder and the recess of the wall surface of the opening has such a shape that an inner side of an outer edge of the recess is concaved into the outer edge, the outer edge at least partially has a shape extending toward a coupling portion between the laser diode holder and the holding portion, and the adhesive agent is applied to the recess, and a width of the recess at the coupling portion in a circumferential direction of the outer circumferential surface of the laser diode holder is the same as a width of the recess at the coupling portion in the circumferential direction of the wall surface of the opening.