An image forming apparatus including: a first and a second photoconductor groups constituted of one or more photoconductors respectively; a first and a second drive control sections for controlling the drive of the first and the second photoconductor groups respectively to rotate the photoconductors thereof, wherein the rotational phases of the first photoconductor group and the second photoconductor group are adjusted to be matched therebetween; and the first and the second drive control sections control so that the first and the second photoconductor groups are driven simultaneously with an equal target speed during a formation of a image, wherein an initial drive speed is lower than a predetermined speed for image-formation, and after the first and the second photoconductor groups reaches the initial drive speed, the target speed is changed from the initial drive speed to the speed for image-formation.