To obtain a uniform coating performance by preventing stagnation of flow in a coating bath when carrying out coating of a multiplicity of base substances in a monobath coating bath simultaneously, increasing the displacement efficiency of a coating liquid, and preventing an increase in the viscosity of the coating liquid.

The present invention is an electrophotographic photoreceptor manufacturing device having a monobath coating bath in which a coating liquid is cast into the coating bath from below by a solution sending device from a coating liquid stock tank 1 and is made to overflow the upper end for controlling the liquid level, and a multiplicity of bases substances of electrophotographic photoreceptors are immersed simultaneously for coating. The monobath coating bath comprises a straight pipe part 9 disposed in the same arrangement for each individual base substance of the photoreceptor, an assembly part 11, and one or more tapered inflow fluid diffusion part 6, and two or more straightening plates 3 are provided to each of the tapered inflow fluid diffusion part 6.