Currently, progress in soft robotics is contributing to advancements in the field of robotics. A soft robot has several advantages over a traditional robot including portability, durability, and increased flexibility. A suitable design of the actuators in a robot is crucial for increasing the robot's flexibility. A suitable design of the actuators present in a robot is crucial for increasing the robot's flexibility. This study aims to develop a soft rat robot based on pneumatic actuators that can interact with real rats. The pneumatic actuator design developed by Suzumori et al. in 2017, the flexible micro actuator (FMA), is chosen as the main actuator to drive the robot. This actuator is rodlike, made using silicone fiber, and driven by filling high-pressure air into a specially designed container. An actuator based on the FMA design with a diameter of 25 mm is fabricated to form a soft rat robot that can simulate the motions of a real rat - rearing and rotating left and right. Finally, the properties of the pneumatic actuator are tested and analyzed to optimize the structure of the robot.