A precision machining method enabling grinding with high accuracy is provided. The method includes a first step of producing an intermediate ground workpiece by roughly grinding a workpiece (a) with a diamond grinding wheel (b), and a second step of producing a final ground workpiece by grinding the intermediate ground workpiece with a grinding wheel for CMG. In the first step, feed of the rotator (6b) and the base (3) is controlled in multiple stages with different feed speeds according to control based on the amount of movement, and in the second step, movement of the rotator (6b) and the base (3) is controlled with a constant pressure or in multiple stages having different constant pressures.