To provide a small optical unit supporting device in which the tilt sensor of the optical unit hardly interferes with the optical unit itself or its luminous flux.

A mirror 6 as an optical unit and coils 15-1 and 15-2 are mounted on individual holders 14 supported in a housing 12 with separate springs 16 extended in an S shape in the direction along the rotation axis 11 so that the mirror and coils can rotate or deform to form a moving part. The surface of the mirror 6 is tilted around the rotation axis 11 by the currents made to flow in the coils 15-1 and 15-2 opposed to the magnet 17 to vary the direction of the reflected light 7 relative to incident light 5. An LED 19 and PSD 20 are disposed on both sides of a plane which contains incident light 5 and reflected light 7 in order to detect the tilt surface of the mirror 6. Thus a structure is obtained in which a tilt sensor can be easily disposed without causing interference with the mirror 6 and its luminous flux.