Abstract: To provide an optical scanning sensor which performs an object detection with high accuracy by suppressing the mutual interference between scanning light and reflection light, the optical scanning sensor comprises a light projecting unit that projects light, an optical scanning actuator that emits the light from the light projecting unit via a reflecting mirror and performs scanning with the light emitted by causing the mirror to swing, and a light receiving unit that receives, via the mirror, reflection light by an external object of scanning light emitted by the optical scanning actuator. The mirror includes a first surface that reflects the light projected by the light projecting unit and emits the light reflected outward as the scanning light, and a second surface that is parallel to and discontinuous in a reflection area with the first surface and reflects and emits the reflection light to the light receiving unit.