PURPOSE: To prevent ghost by reflected light on the surface of a filter and to make the adhesion of the filter firm by bending the light transmissive area of the filter and fixing it to a stop blade with two kinds of adhesives having different viscosity.

CONSTITUTION: The ND filter 4 of this device is made to adhere to the stop blade 3a in a state that the light transmissive area 4a of the filter 4 is is bent or curved with reference to the blade 3a. After a gap between the filter 4 and the blade 3a is filled with the adhesive 6a having low viscosity so that the filter 4 and the blade 3a may tightly adhere not to form the gap, the edge part of the filter 4 and the blade 3a are made to adhere to each other with the adhesive 6b having high viscosity. It is desirable to bend the filter by forming a notch at the root of the area 4a in such a method that a tool 7 having edgelike tip is pressed to the filter 4.