An object detection device comprising: a light source ; a light deflector that scans a scanning area with light emitted from the light source ; an imaging forming optical system ; and a light-receiving unit comprising a photodetector , the light receiving unit configured such that, when an object is present in the scanning area, receives reflected light from the object through the imaging forming optical system , wherein, the light emitted from the light source is emitted to the object so as to irradiate an area having a shape longer in a second direction orthogonal to a first direction than in the first direction, and a focal length of the imaging forming optical system in the first direction and that in the second direction are different from each other, said object detection device being characterized in that : Wpds/Wpdm<Wes/Wem is satisfied, where Wpdm is a length of the light-receiving region of the photodetector in the first direction, Wpds is a length of the light-receiving region of the photodetector in the second direction, Wem is a length of the area irradiated with the light emitted to the object, in the first direction, and Wes is a length of the area irradiated with the light emitted to the object, in the second direction, and the length Wpds of the light-receiving region in the second direction is longer than the length Wpdm of the light-receiving region in the first direction. a light source ; a light deflector that scans a scanning area with light emitted from the light source ; an imaging forming optical system ; and a light-receiving unit comprising a photodetector , the light receiving unit configured such that, when an object is present in the scanning area, receives reflected light from the object through the imaging forming optical system , wherein, the light emitted from the light source is emitted to the object so as to irradiate an area having a shape longer in a second direction orthogonal to a first direction than in the first direction, and a focal length of the imaging forming optical system in the first direction and that in the second direction are different from each other, said object detection device being characterized in that : Wpds/Wpdm<Wes/Wem is satisfied, where Wpdm is a length of the light-receiving region of the photodetector in the first direction, Wpds is a length of the light-receiving region of the photodetector in the second direction, Wem is a length of the area irradiated with the light emitted to the object, in the first direction, and Wes is a length of the area irradiated with the light emitted to the object, in the second direction, and the length Wpds of the light-receiving region in the second direction is longer than the length Wpdm of the light-receiving region in the first direction. Wpds/Wpdm<Wes/Wem is satisfied, where Wpdm is a length of the light-receiving region of the photodetector in the first direction, Wpds is a length of the light-receiving region of the photodetector in the second direction, Wem is a length of the area irradiated with the light emitted to the object, in the first direction, and Wes is a length of the area irradiated with the light emitted to the object, in the second direction, and the length Wpds of the light-receiving region in the second direction is longer than the length Wpdm of the light-receiving region in the first direction. <EOS>