PURPOSE: To detect movement of the eyes while visual stimulation is given and to detect movement of the eyes while an exterior scenary is observed.

CONSTITUTION: A hot mirror 3 reflecting infrared rays and transmitting a visible light and an infrared rays camera 5 which takes a photographs of the eyes 4 of an object with the infrared rays irradiated from an LED 2 and reflected by means of the hot mirror 3 are provided. The hot mirror 3 is positioned at the front of the eyes 4 and the infrared rays camera 5 is positioned at a position where the front range of vision of the object is not obstructed.