PURPOSE: To provide the image rotator device which removes/inserts an image rotator from/to the optical path in a limited space.

CONSTITUTION: A rotating cylinder 3 whose revolving shaft coincides with the optical axis of an astronomical telescope is provided. A support revolving shaft 6a of an image rotator unit 5a is provided in parallel with the revolving shaft of the rotating cylinder 3 and in an eccentric position for the purpose of inserting/removing image rotators M1, M2, and M3 to/from the optical axis. Another image rotator unit 5b provided with a support revolving shaft 6b is provided axially symmetrically to the support revolving shaft 6a of the image rotator unit 5a with respect to the revolving shaft of the rotating cylinder 3.