An object detection device includes: a light deflector that scans a scanning area with light emitted from a light source; and a light-receiving unit that, when an object is present in the scanning area, receives reflected light from the object through an imaging forming optical system. The light emitted from the light source irradiates an area having a shape longer in a second direction orthogonal to a first direction than in the first direction. Wpds/Wpdm