A machine control system comprising a machine body (2), at least one exchange module (3,4) mounted to said machine body (2) in an interchangeable manner, storage means (3b,4b) provided in said exchange module (3,4) for storing an action library of said exchange (3,4) module, and action decision means (2e) and storage means (2b) provided in said machine body (2). Said action decision means (2e) being adapted to decide actions of the exchange module (3,4) according to said action library and said storage means (2b) being adapted to store said action library, and that when said exchange module (3,4) is replaced, an action library in said machine body (2) is rewritten with the action library of said new exchange module (3,4).