A controller calculates first movement times when moving each robot hand from a movement start position to a synchronous operation position in a shortest time and decides the longest first movement time as a second movement time. The controller generates, for each robot, a robot operation plan for moving each robot hand without stopping from the movement start position to the synchronous operation position in the second movement time. The robot hand of each robot moves from the movement start position to the synchronous operation position without stopping and simultaneously reach the synchronous operation positions.