To provide a simple image reducing apparatus which reproduces an original image excellently and not requiring much processing time and to provide an image forming apparatus provided with the image reducing apparatus.

The image reducing apparatus 10 is provided with a reduction processing circuit 10a that specifies, by a prescribed method, a thinned pixel in accordance with a reduction rate, performs black/white coincidence discrimination between the specified thinned pixel and a pixel adjacent thereto, replaces the adjacent pixel with a permissible maximum value or minimum value when coincidence is found, or replaces the adjacent pixel with medium tone data when no coincidence is found, and generates multi-value data wherein a value range including the permissible maximum value, the permissible minimum value, and the medium tone data are defined in advance.