An occurrence space 32A which is provided in a light shielding space 3A shielded from light from an outside and into which a detection target flows, a first light emitting unit 61A and a second light emitting unit that emit detection light along a first light emitting-side optical axis 611A and a second light emitting-side optical axis toward an occurrence space 32A, a light receiving unit that receives scattered light generated when detection light emitted from the first light emitting unit 61A and the second light emitting unit is scattered by a detection target flowing into the occurrence space 32A along a light receiving-side optical axis intersecting the first light emitting-side optical axis 611A and the second light emitting-side optical axis, and a smoke detection unit cover-side inclined portion 43A that primarily reflects the detection light emitted from the first light emitting unit 61A and the second light emitting unit in a direction intersecting a plane defined by the first light emitting-side optical axis 611A, the second light emitting-side optical axis, and the light receiving-side optical axis are included.