The strain range of rubber products is very large. Conventional strain sensors have limitations in measuring large strain of rubber. Therefore, it is necessary to develop a strain sensor capable of measuring a high strain range. In this study, we have been developing and studying a highly flexible strain sensor using Multi-Walled Carbon Nanotube (MWCNT CM-250) and PolyUrethane(PU) as a base material matrix. The fabricated strain sensor has higher elongation and shrinkage than conventional strain sensors. In addition, the sensitivity and stability of the sensor signal can be controlled by varying the length, height, width and content of filler MWCNT. The fabricated sensor was attached to the specimen and subjected to tensile test. Experimental results show that the fabricated sensor has high elasticity but low zero drift and hysteresis compared to conventional strain sensors.