In this study, we propose and develop PDMS-based modular actuators. The microactuator which looks like small insect uses thermal expansion power of the PDMS (polydimethylsiloxane; sylgar？184 silicone elastomer). The PDMS-based microactuator provides a large displacement due to a high thermal expansion coefficient (approximately 310ppm). The microactuator with 1mm length 350μm width is optimized by using a numerical analysis. The shape of the PDMS actuatoris variously designed. They are placed at several positions to find optimal position that provides a high transformation ratio. The PDMS-based microactuators are fabricated using conventional micromaching technique. The fabricated microactuator is heated using a hot-plate. The actuator displacement is measured as a function of temperature from 27℃ to 300 ℃. The experimental results compared to the simulation result. When heating temperature up to 300℃ is applied to the PDMS actuator, each V-groove-shaped joint is actuated 30μmat 300°C. Anotherdesign of the microactuator has a maximum displacement of about 656mm.