A simulation apparatus convenient for evaluating, correcting, etc. a program for a robot system including a visual sensor, wherein a work cell is defined on the simulation apparatus (10) and a robot (1) mounting an image capturing device (2), a workpiece (3), etc. are arranged in it; a separately set visual volume model (30) is introduced into it, a tool coordinate system (tool tip point) is defined at a view point (23), and a detection reference point (detection reference coordinate system) (24) relating to the workpiece (3) is set; and a graphic jog is performed to make the robot (1) move so that the tool coordinate system matches with the detection reference coordinate system, the above process is displayed on a first screen (4-1) and the image viewed from the image capturing device (2) is displayed on a second screen (4-2). A simulated correction amount by the visual sensor is designated and the display of the visual volume model (30) is switched on and off in accordance with output/nonoutput of the image capturing command at the time of simulation of the operation program.