PURPOSE: To change the color of a sample and the background widely, by providing a housing as an attachment that fitted with an ocular mirror incorporated with a polarizing plate, a special filter having a lamination of cellophane, and a polarizing plate.

CONSTITUTION: Polarizing plate 1 is built in ocular mirror 4. In bottom plate 64 of housing 6, polarizing plate 2 is incorporated and between polarizing plate 2 and sample table 61, special filter 3 sandwhiched in between two glass plates while the optical axes of the polarization of cellophane films are shifted by a desired angle is rotatably incorporated by holding cylinder 32. Ocular mirror 4 is fitted in a microscope and housing 6 is fixed at the prescribed position of stage 5 by spring 50a of sample setter 50. A sample is observed while the special filter is torated by operation lever 36. Consequently, the color of the sample and the background are changed widely.