A simulation apparatus includes a simulation management unit for designating an elapsed time point, a robot operation calculation unit for causing the operation program to be executed to a designated elapsed time point to determine the operating position of the robot at the designated elapsed time point, a machine tool operation calculation unit for sequentially determining the operating position of the machine tool while at the same time executing the machining program continuously, and a machine tool operation storage unit for storing the determined operating position of the machine tool in correspondence with the elapsed time point each time a unit time elapses. The simulation management unit displays three-dimensional models of the robot and the machine tool on a display unit based on the operating positions of the robot and the machine tool at the designated elapsed time point acquired from the robot operation calculation unit and the machine tool operation calculation unit.