A processing device includes: a frame that supports a photosensitive drum; a bearing member that biases a charge roller in the direction to be in contact with the photosensitive drum; and a holder that is switchable between a holding state where the charge roller is separated from the photosensitive drum and a canceled state where the holding state is canceled so that the roller is brought into contact with the photosensitive drum; wherein a canceling member is provided in at least one of inside the processing-device attachment and an attachment body attached to an image forming apparatus main body at a front side to cause the holder to shift from the holding state to the canceled state. The canceling member causes the holder to shift from the holding state to the canceled state when the attachment body is attached to the image forming apparatus main body at the front side.