To increase a stirring capacity and to prevent a slit from being closed by a temp. change by specifying the shape of this slit.

The processing liquid is injected from the slit S formed in a chamber 74 to a photosensitive material, by which the processing liquid in a processing tank is stirred. The slit S is so formed as to intersect orthogonally with the transporting direction of the photosensitive material. The opening width of the slit S is set at 0.1 to 2.0mm and the opening length thereof at ≤40m (more preferably 10 to 30mm). The opening width of the slit S is narrowed in such a manner, by which the injection force of the processing liquid is increased and stirring efficiency is enhanced even if the pressure of the processing liquid to be sent to the chamber 4 is not increased. The working of the slit S is made easy by shortening the opening length. The closing of the slit S by a temp. change is thus averted.