In an image forming apparatus capable of selectively carrying out a color print mode or a monochromatic print mode, the individual print modes are carried out as follows. In the color print mode, images are arranged on an intermediate transfer belt 71 with a first spacing d1(a) suited for the color print mode, the first spacing shorter than a second spacing d2(a). Hence, the second spacing d2(a) may be increased by the amount that the first spacing d1(a) is decreased, so that a sufficient time for the changeover of developers 4Y, 4M, 4C, 4K may be afforded. In the monochromatic print mode, on the other hand, adjustment is made to equate the first spacing d1(a) to the second spacing d2(a). This obviates a narrowed sheet spacing.