A rotating electric machine driving apparatus includes a controller section that obtains an electric current detection value and generates instruction signals for switching ON and OFF of switching elements based on the electric current detection value. The web drying apparatus generally comprises at least three substantially axially parallel rotatable drying cylinders, first and third cylinders being vertically offset from a second cylinder and the web being consecutively trained thereover defining the pocket therebetween. Different clearances are set between the pressure regulating member, and the outer annular valve seat portion and the inner annular valve seat portion, such that when the pressure regulating member abuts against one of the valve seat portions, a small gap is formed between the other valve seat portion and the pressure regulating member.