PURPOSE: To provide a polishing device performing super-precision machining with a high accuracy while controlling the machined quantity of a workpiece and the wear quantity of a tool efficiently without causing a flaw to the surface of the workpiece and without any harm to a human body.

CONSTITUTION: In this polishing device, voltage is applied between a tool 3 mounted to the spindle 1 of a machine tool and a workpiece 9 submerged in electrolyte 7, stored in a machining tank 5 with abrasive grain dispersed therein, so as to cause an electrophoretic phenomenon to machine the workpiece 9 in the electrolyte 7. The tool 3 is formed of polymeric material obtained by mixing carbon fiber in thermoplastic resin, and the electrolyte 7 is polymeric electrolyte obtained by dissolving calboxymethylcellulose sodium (CMC) and abrasive grain of about 10μm in diameter in water. The polishing device is also provided with a voltage variable power unit 25.