To provide a film developing device equipped with a liquid temperature regulating device which is simple in structure, is low in a cost, is easy in maintenance, is low in noise and is capable of regulating the liquid by cooling or heating the liquid in a liquid tank so as to attain the temperature within the prescribed range.

The liquid temperature regulating device consists of a liquid circulating pipeline 2 which communicates with the upper segments to the respective bottom segments of the developer liquid tank 21 and fixer tank 22 of a tank body 20, a liquid pump 3 for circulation which is interposed in mid-way of the liquid circulating pipeline 2, a heat exchange pipe 4b which is interposed into the downstream side of the liquid pump 3 for circulation of the liquid circulating pipeline 2 and is embedded into a heat transfer block 4a, a thermo- module 4c which consists of a Peltier element fastened to one flank of the heat transfer block 4a and a fan 4e which sends air to the heat radiation side of this thermo-module 4c.