A simulation device capable of easily constructing the layout of a three-dimensional model of a robot system in a virtual space. The simulation device includes a model arranging section that arranges a component model in a virtual space, the component model being a three-dimensional model of a component of the robot system; a reference setting section that sets a reference point, a reference axis, or a reference plane in the virtual space; a symmetric model generation section that generates a symmetric component model of the component model arranged in the virtual space, the symmetric component model being a three-dimensional model symmetric with respect to the reference point, the reference axis, or the reference plane; and a simulation section that executes a simulation to simulatively operate the component model and the symmetric component model in the virtual space.