PURPOSE: To prevent a lowering of a resolution by setting specifically the second plane mirror to the first turnable plane mirror for reflecting an object to be measured, irradiated by a light source, and executing an image pickup.

CONSTITUTION: The frist plane mirror for reflecting an object to be measured 2 irradiated by a light source device 1 is made turnable, the second plane mirror 5 is placed opposingly so as to be turnable to a mirror 3 by a separated distance equal to a separated distance between the object 2 and the mirror 3, its turning quantity is controlled to half of a turning quantity of the mirror 3, and an image pickup is executed by an image sensor device 4. In this way, a movement of an image of the object 2 following the turning of the mirror 3 can be eliminated by a mirror 5, therefore, a field of a view of the device 4 can be limited.