PURPOSE: To prevent the interference caused between the machines without using an interference preventing program by carrying out the interlock control after deciding the interference state between an action unable area and a mobile area based on the present position and an estimated position.

CONSTITUTION: The position sensors 9 are connected to the rotary shafts of the servo motors 8 and detect the present positions respectively. The controllers 1 read the control programs of machines A and B out of each built-in memory and output the target position data PP on the motors 8 to the position command parts 2 to perform the positioning control. The position computing parts 6 convert the output of the sensors 9 into the present position data P1. The position estimating parts 11 estimate the machine positions to be set after a prescribed time based on the data P1. Then the area production parts 12 produce the area data AA and AB for the movements of both machines A and B between the present and estimated positions and output these data to an interlock control part 20. The part 20 supplies the area data AD through an area designating part 10 to decide the interference state among those areas AA, AB and AD and then carries out the avoidance processing against the interference if caused among these areas.