PURPOSE: To obtain a small-sized, simple image rotator which eliminates the need to correct the bending of on optical axis by setting properly the lens length and refractive index distribution of an optical member which has a refractive index distribution in only one of two directions perpendicular to the optical axis.

CONSTITUTION: The optical member 2 has the refractive index distribution in only one of the two mutually orthogonal directions perpendicular to the optical axis. Then when the lens length and refractive index distribution are so set properly that the projection luminous flux image of the optical member 2 is in mirror image relation with an incident luminous flux image, the light is converged on a node 5 in the XZ section and then projected as parallel luminous flux 3, and the light is inverted without bending the optical axis 6. Further, the light is projected as it is in the XY section without changing in the member 2. Consequently, the projection luminous image can be rotated by rotating the optical member 2 and the small-sized, simple image rotator is obtained which eliminates the need to correct the bending of the optical axis.