PURPOSE: To perform highly accurate flat work automatically in an efficient manner, by turning each work arriving at the specified position, with a rotary head individually and discharging it automatically, while installing a flatness correcting ring which rotates with turning force in a work surface.

CONSTITUTION: Each work 11 is fed to each holder one by one, and at the point where four works 11 reach to a carrying-in side route part, rotation in a chain 8 comes to a stop, causing a working head 23 to go down, and each rotary head 22 is pressed to each corresponding work 11 whereby an elastic body 27 pushingly hits the top surface of a large diametral disc part 12 of the work 11, while a small diametral part 13 gets into a hollow part of the elastic body 27, and a boss 28 is fitted into a small hole 14 so that the work 11 is machined upon pressing it to a work surface 2 as being rotated. When machining is over, the working head goes up, and the chain 8 rotates again, transferring each work 11 and automatically discharging it out. On the other hand, flatness on the work surface is corrected by a correction ring which rotates by turning force of a working tool 1.