Abstract: In a control system for synchronous rotation of the cutter heads in a multi-cutter shield machine, the rotation cutter heads are so disposed in generally the same plane such that the distance between the centers of the adjoining cutter heads is larger than the radius, and smaller than the diameter, of the cutter heads. The rotating cutter heads are driven independently of each other by electric drive systems, respectively. Each of the electric drive systems consists of plural motors with a reduction gear, coupled to the respective rotating cutter heads by means of a pinion and gear. The motor rotation is so controlled and the cutter heads are so synchronously rotated, that the angle of deviation between the cutter heads is within such an allowable range that the cutter heads will not interfere with each other even if there is any imbalance in excavating and rotating resistances between the cutter heads.