An optical sensing device includes a shell, at least one light emitting member, a rotating type shading assembly and at least one optical sensing member. The shell is formed with a black-body condition space having a light emitting chamber, a shading chamber and at least one optical sensing chamber. The light emitting member projects a light beam. The rotating type shading assembly includes a pivot and a shading member. The shading member is pivotally connected to the pivot in the shading chamber, and has a weight center offset from the pivot center. When the optical sensing device is tilted, the shading member is rotated to make the weight center located in a lowering azimuth with respect to the pivot. The optical sensing member is arranged in the optical sensing chamber, and senses the light beam to accordingly send out a sensing signal.