A regulating device and method regulating the thickness of a toner of an image forming apparatus. The bottom pole tip is formed on a flat surface of the bottom pole layer, and insulating layers made of inorganic materials are buried in a concave part between the bottom pole tip and a bottom connecting portion. The cylinder body is formed with an exhaust port communicating with the first chamber, an operation port communicating with the second chamber, and a purge port communicating with a fluid non-contact chamber.