To reduce a cost of a measuring device, and improve measuring accuracy in wheel alignment measurement to measure a dynamic vibration component.

A driving detecting unit 6 is driven so that a distance of a measuring unit 4 up to a plane to constitute a reflecting unit 5 becomes almost constant on the basis of an output signal of the measuring unit 4, and a data processing control unit 7 calculates a displacement quantity of a tire wheel 3 on the basis of a distance of the measuring unit 4 up to the plane to constitute the reflecting unit 5 on the reflecting unit 4 driven by the driving detecting unit 6. Therefore, though both a static vibration component having large amplitude and a low frequency and a dynamic vibration component having small amplitude and a high frequency are contained as the displacement quantity, the dynamic vibration component is offset in a laser displacement gauge to constitute the measuring unit 4, and only the dynamic vibration component is detected as a distant measuring signal of the laser displacement gauge, and a measurable distance range of the laser displacement gauge can be shortened, and an inexpensive device can be constituted without deteriorating measuring accuracy.