for driving transport rollers 21 and a photosensitive material processing calculator 38 for calculating the amount of photosensitive material to be processed based on the transport speed of the film and a signal from sensor 36 the control device 13 setting unit 35 and controller 39 are controlled by a cpu 40 the isolation box 15 fig5 is disposed in an upper portion of the fixing tank 2 the introduction pipe 12a for introducing the chemical a is provided in the fixing tank 2 while the pipes 12b and 12c for introducing the chemical b and water c are provided in the isolation box 15 the chemical b is diluted in a dilute ratio specified by a chemical manufacturer about several ten times in the isolation box 15 the diluted liquid overflows from the isolation box 15 into the fixing tank 2 the isolation box 15 has already been filled with a diluting solution supply of the chemical b and water c to the isolation box 16 so filled causes the diluted chemical b to be sequentially supplied into the fixing solution f an overflow pipe 16 keeps the level of the fixing solution f lower than that of the isolation box 15 this ensures that components of the fixing solution f do not enter the pipe 12b and therefore do not clog the pipe 12b with precipitated crystals with the present invention crystallization hardly occurs since the raw liquid chemical b does not contact the chemical a or the fixing solution f rather the chemical b is first diluted several ten times with water and then contacts the mother liquor f after replenishment of the chemicals a and b is completed the chemical b and mother liquor f react with.