OPTICAL SCANNING DEVICE, IMAGE PROJECTION DEVICE, AND MOBILE OBJECT

An optical scanning device includes: a light source; a scanning unit configured to deflect light from the light source in a main scanning direction to scan a scanned area with light; an optical member configured to guide light from the light source to the scanning unit; a casing holding the light source and the optical member; and an attaching part disposed between the optical member and the casing to attach a part of the optical member to the casing, wherein a direction in which the attaching part is interposed aligns with a direction corresponding to the main scanning direction of the scanning unit.