The system behavior is evaluated by checking the position and the orientation of a target processed by a processing device in accordance with a control instruction. A simulator estimates a behavior of a system including a processing device that processes a target. The simulator includes a measurement unit that performs image measurement of an input image including at least a part of a target as a subject of the image, an execution unit that executes a control operation for generating a control instruction directed to the processing device based on a measurement result obtained by the measurement unit, and a reproduction unit that reproduces, in the system, a behavior of a target detected in the input image together with information about a type and an orientation of the target based on time-series data for the control instruction output from the execution unit and the measurement result from the measurement unit.