PURPOSE: To make it possible to stably fix animal eye balls and also adjusting of a pressure on the eye balls.

CONSTITUTION: A support base 9 links an outer cylinder 11 and an inner cylinder 13 through a bottom part 15. A plurality of support pieces 19 are provided at an open end of the inner cylinder 13. Support pieces 23 of four contact pieces 21 arranged in a ring are fitted into the respective support pieces 19. The respective contact pieces 21 form a spherical housing part E of an eye ball 31. An energizing cylinder 25 and an energizing spring 27 in the inner cylinder 13 energize the contact pieces 21 in such a direction as to contact the support pieces 23 to expand. A press adjusting cylinder 33 is screwed into the outer circumference of the outer cylinder 11 to make the contact pieces 21 stick out from adjusting holes 35 of the press adjusting cylinder 33. When the press adjusting cylinder 33 is turned being pulled out of the outer cylinder 11, the adjusting holes 35 presses the respective contact pieces 21 to hold the eye ball 31 of the spherical housing section 6 being pressed from the perimeter thereof.