PURPOSE: To provide a spatial frequency characteristic varying device capable of optically changing a spatial frequency characteristic by providing a means for hourly changing a relative position of an image formed on a light receiving surface with respect to the light receiving surface.

CONSTITUTION: A variable vertical angle prism 3 is constituted of a pair of glass plates 31, 32 facing to each other separated in the direction of an optical axis, a bellows member 33 for connecting the outer peripheral parts of the glass plates 31, 32 and forming a sealed space and a fluid (e.g. silicone oil, etc.,) 34 with a prescribed refractive index filled into the space surrounded by the glass plates 31, 32 and the bellows member 33, and it is an optical element capable of displacing the optical axis 5 by moving the glass plate 32 by a drive system 6. In such a case, the variable vertical angle prism 3 and the drive system 6 are used as to the spatial frequency characteristic varying device. Then, by that the same images are formed on at least two positions of the light receiving surface, the spatial frequency characteristic of the image obtained by a total sum of image forming times in respective positions is varied.