PURPOSE: To prevent the wear of a supply roll and a developing roll, by spacing the supply roll from the developing roll while a developing device is not in operation, mounting the supply roll to one end of a lever and a cam follower to the other end, providing the 2nd cam for turning and operating the lever to a dial shaft having the 1st cam, and setting adequately the phase difference between both cams.

CONSTITUTION: While a developing device is not in operation, both of a supply roll 14 and a pressurizing blade 12 are parted from a developing roll 11 to prevent distortion, the deterioration in a contact part or the change of pressurizing force with time, and permanent set. When the developing device is then started, the roll 14 is brought into press contact or contact with the roll 11; therefore, the generation of unnecessary friction is obviated. A developing soln. is coated and supplied on the roll 11 from the starting, and since the first photosensitive paper is conveyed to the position of the roll 11 with some delay, the developing soln. is uniformly coated on both of the roll 11 and the roll 14, before the blade 12 is held in press contact or contact with the roll 11. Thus, when the photosensitive paper is conveyed along a guide plate 10, the blade 12 is brought into press contact or contact with the roll 11 by a switch 26, the developing without unevenness is accomplished from the first photosensitive paper.