A numerical control apparatus can perform a machining simulation or an interference check that reflects worksite information. However, a machining simulation apparatus cannot use worksite information in a machining simulation or an interference check. Thus, simulation conditions of the machining simulation apparatus are different from those of the numerical control apparatus. To solve this problem, a machining simulation apparatus and a numerical control apparatus according to the present invention can communicate with each other via a communication unit or a storage medium so as to mutually transmit and receive data. The machining simulation apparatus includes a network transmission/reception control unit or an external memory reading/writing unit. Similarly, the numerical control apparatus includes a network transmission/reception control unit or an external memory reading/writing unit.