An object detector and a sensing apparatus are provided. The object detector includes a light source, a light deflector configured to deflect light emitted from the light source, and a photodetector configured to detect the light that is deflected by the light deflector and then is reflected at an object, where the light deflector includes a plurality of reflection planes that rotate on a rotation axis, the reflection planes are oblique to the rotation axis and are rotationally symmetrical about the rotation axis, and the light that is emitted from the light source enters the light deflector in a direction parallel to the rotation axis. The sensing apparatus includes the object detector, and a monitoring controller configured to determine whether an object is present, and obtain movement information of the object including at least one of moving direction and moving speed of the object.