A simulation apparatus 1 includes a touch panel 20, a display controller 11, a display screen data storage unit 12, an input control unit 13, an operation information storage unit 14, a model data storage 16, a simulation executor 15 and an NC program generator 17. The simulation executor 15 displays an image of a movable structure 12 to be operated on the touch panel 20, moves the image in accordance with a manual operation and checks occurrence of interference, and, in the case where interference occurs, stops the movement of the image and displays the occurrence of interference on the touch panel 20. Further, in the case where it is confirmed that no interference occurs, the NC program generator 17 generates an NC program based on manual operation information.