3D simulators for mobile robots serve as tools for operation training. The present paper reports on a simulated serpentine robot in a 3D simulator. A simulated robot is IRS Soryu, which is a search robot composed of three connected cars and has been expected as a search robot for narrow spaces in disaster areas. An adopted 3D simulator is USARSim, which is a high fidelity 3D simulator for mobile robots on the basis of a commercial game engine. Qualitative validation of the simulated robot was conducted in order to examine that the simulated robot is available for operation training of the real robot. The experimental results showed that the simulated robot had similar traveling performance to the real robot.