PURPOSE: To apply a proper amount of release liquid to the roller of a toner image fixing device automatically by putting the tip of a conductive, small- diameter nozzle opposite to a rotating body closely, and coating the rotating body with the release liquid from the tip of the nozzle while applying a voltage to the nozzle.

CONSTITUTION: The nozzle 5 made of stainless steel fitted atop of a tube 4 is arranged closely to a fixing roller 1 so that the prolongation of the nozzle 5 crosses the circumferential surface of the fixing roller 1 at right angles, the nozzle is reciprocated by a moving mechanism in the lengthwise direction of the fixing roller 1, and the nozzle 5 is moved forth and back once in the lengthwise direction of the roller 1 every time the roller 1 rotates 50 times. The nozzle 5 is connected to a variable voltage source E to supply the release liquid 7 in a container 6 to the roller 1, and the amount of release liquid to be supplied is determined by the surface potential V of the fixing roller 1 and the voltage NN applied to the nozzle 5.