This chapter explains how the MEMS microrobot system could perform the walking behavior of ants. MEMS microrobot system consists of micro-mechanical systems and micro-electro systems. The micro-mechanical systems mimic the alternating tripod gait of an ant by the shape memory alloy-type rotary actuator and the link mechanism. The micro-electro systems mimic the electrical activity of biological neural networks using the artificial neural networks IC. The artificial neural networks IC generates the driving pulses of shape memory alloy-type rotary actuator without using software programs. The micro-mechanical systems and micro-electro systems are integrated as a robot system. As a result, the authors show that the MEMS microrobot system could perform the ant-like walking behavior with a speed of 20 mm/min. The MEMS microrobot system was 0.079 g in weight, 4 mm width, 4 mm length, and 5 mm height in size. The robot system needs only the electrical power source as an external device.