PURPOSE: To improve productivity and grade of mirror face and to prolong life of cutting tools by performing rough cutting and finish cutting with 1-axis-plural edges.

CONSTITUTION: In a construction of main shaft system of a mirror face machining device, two kinds of cutting tools 13, 14 are mounted on a rotary board 2 so as to cut a member to be machined 19 roughly with a rough cutting tool 14 first and to perform finish machining of the mirror face with a finish cutting tool 13. Next, the condition where a min cutting edge (θ1)20 of the cutting tool 14 is set to θ1 (main cutting angle) to the feed direction of the member 19 is shown. A main cutting edge (θ)15 of the cutting tool 13 is also set to a positive angle of θ (main cutting angle) similarly. When the cutting edge (θ1)20 of the cutting tool 14 is set to a positive angle of θ1 (main cutting angle), a main cutting face (θ1)22 can be formed. By this construction, productivity and grade of mirror face can be improved and life of cutting edges can be prolonged.