Image-forming device

An image-forming device comprising:

• an outer frame;
• a plurality of photosensitive drums disposed inside the outer frame;
• a drum gear provided on an axial end of each photosensitive drum and rotatable together with each photosensitive drum, the drum gear having gear teeth;
• a drum gear rotating body that rotates together with the drum gear and has a peripheral surface provided with a protrusion;
• a drum drive gear drivingly rotatably supported on the outer frame and meshedly engaged with the drum gear, the drum drive gear having gear teeth whose number is the same as that of the gear teeth of the drum gear;
• and
• a drum drive gear rotating body rotatable together with the drum drive gear, the drum drive gear rotating body having a peripheral surface in alignment with the peripheral surface of the drum gear rotating body and formed with a depression engageable with the protrusion at a specific angular rotational phase of the drive gear and the drum drive gear, one of the drum gear and the drum drive gear being movable in a direction away from remaining one of the drum gear and the drum drive gear when the protrusion rides up on the peripheral surface other than the depression of the drum drive gear rotating body, to disengage the drum gear from the drum drive gear and to stop rotation of the drum gear at an angular rotational phase of the drive gear and the drum drive gear other than the specific angular rotational phase.