To solve problems that it is difficult to control the flow of an electrolytic solution on the surface of an electrode to a fixed flow in a conventional batch method, film distribution is made frequently ununiform and reproducibility between films is deteriorated especially in the case of manufacturing a thin film (e.g. ≤1μm), and although a method utilizing a flow cell has a merit that the flow of the electrolytic solution can be controlled with high reproducibility, it is difficult to control a film formation speed at fixed speed, ununiformity of film distribution and film defects may be easily generated and reproducibility also is deteriorated in a conventional method for forming a bio-sensor film (composite film of polypyrrole and an enzyme) by electrolytic polymerization.

In the manufacturing method for performing electrolytic polymerization while feeding the electrolytic solution under a condition that the ratio of an electrolytic speed to the flow rate of the electrolytic solution in the vicinity of the surface of an electrode is ≥0.4mA/cm2:1cm/min, a film having uniform distribution and high reproducibility can be manufactured.