A mobile robot including a light emitting unit, a processing unit, an optical component, an image sensing unit, a control unit and a moving unit is provided. The light emitting unit emits a main beam. The processing unit diverges the main beam to a plurality of sub-beams. The sub-beams constitute a light covering an area. When a portion of the sub-beams irradiate a first object, the first object reflects the sub-beam and a plurality of reflected beams are reflected. The optical component receives the reflected beams and converges it to a first collected beam. The image sensing unit converts the first collected beam into a first detection result. The control unit calculates depth information according to the first detection result. The control unit activates the relevant behavior of the mobile robot according to the depth information and controls the mobile robot through the moving unit.