To usefully use respective color printing materials by uniformly consuming them.

The image forming apparatus is in a standby state while detecting the residual amount of the printing material (S1), when detecting a change in the residual amount (S2), the processing starts. One or more target images to be printed are retrieved from image information DB 1 based on the residual amount ratio with reference to respective color printing materials (S3). When the target image is selected (S4), the rough consumption of the printing materials is estimated (S5). In this case, a printing condition such as the number of sheets to be printed required to uniformize the residual amount of the printing materials is confirmed, and the confirmed condition is reflected in the printing condition setting (S6). The user sets the printing condition (S7) and urges to execute the printing operation (S8). The image printing operation is executed in the selected setting (S9). In the case of continuously printing a plurality of images, the first image is selected, the printing condition for the selected image is set, the residual amount is detected, the consumption is estimated, then, the printing operation is executed. Next, the second images are retrieved based on the consumption, then, the image to be printed is selected out of the second images. The printing condition is automatically preset from the printing condition for the first image, then, the printing operation is executed.