To facilitate a removal of sludge and to dissolve clogging by carrying out a polishing processing while a processing fluid to which ultrasonic vibration is imparted is fed to a contact border surface of an optical element and a tool.

Water 21 is pumped from a tank 22 by a pump 23 and is fed from a discharge port 116 of an ultrasonic nozzle 25 to a contact border surface of a lens 2 and a fixed abrasive grain tool 11. At this time, an output is imparted to a vibrator 24 by an ultrasonic oscillator 26 and the vibrator 24 starts to vibrate. Ultrasonic vibration in which a vibration direction is superposed is imparted to water 21 by an oscillation of the vibrator 24. A concave spherical surface of a glass lens 2 is contacted with a surface of the fixed abrasive grain tool 11 and they are relatively moved. Thereby, a polishing processing is carried out. At this time, by feeding water 21 to which a ultrasonic vibration is imparted toward the contact border surface, a sludge is not adhered to the tool 11 surface and a lens surface and can be immediately removed even if it is adhered thereto.