We report the electrical resistive response of an elastomeric composite material, composed of poly(dimethylsiloxane) (PDMS) and multi-walled carbon nanotubes (MWCNTs), to large mechanical deformations. A nanocomposite pattern was embedded in bulk PDMS to work as a strain sensor, and the device was fabricated with simplicity through microcontact printing and cast molding techniques. Testing of the device revealed a significant and consistent change in its resistance subject to large tensile strains (>45%). Some peculiar hysteresis effects of resistance response were observed during the course of characterization. To reveal underlying polymeric mechanisms, stress and resistance of bulk polymer nanocomposite samples were tested under various conditions. As a result, the resistance was found to be dependent on a number of factors such as stress, strain rate and strain history or time. Likewise, stress was also found to be possibly dependent on the same variables.