PURPOSE: To arrange a distance required for work holding action of a robot to a minimum limit, by arranging plural rotary work feeders in a layer-built state.

CONSTITUTION: A work on the first work feeder 10 is moved to a prescribed position and stopped, in this position, a robot holds the required work to feed the work into a machine tool. In this way, a pallet is moved and stopped, and holding of the work is successively repeated to continue work. When the robot tends to hold a work from the second work feeder 1'0, an arm of the robot is horizontally moved to the left direction further vertically moved downward, and a required work on the second work feeder 1'0 can be held, then the same action as performed in the first work feeder 10 is repeated, in this way, the work holding action is only required to be continued.