PURPOSE: To improve the safety and the reliability of an apparatus by not burying the apparatus in a developing solution thereby to obtain a highly accurate detecting value of the concentration.
CONSTITUTION: The apparatus is provided with a concentration measuring roller 601, a Mylar 602 for regulating the amount of a developing solution adhering to the roller 601, a lamp 604 and a photodetecting element 605. The roller 601 has the surface formed of a body which reflects light, greatly. The lamp 604 casts light, to the developing solution on the roller 601 after regulated by the Mylar 602 outside a storing part of the developing solution, and detects the concentration of the solution from the transmittance of light obtained from the reflecting light.
OGAWA KAZUO
SOGA HIROSHI
