We developed a low-cost flexible pressure sensor based on an elastomer film with uniformly distributed micro-pores as a dielectric layer. The dispersion of the micro-pores in the elastomer film results from the phase separation between a prepolymer material and deionized water to the elastomer, followed by the subsequent evaporation of the solvent within the polymer matrix after polymerization. Owing to the enhanced deformability by the pore structures, the relatively high sensitivity of 1.18kPa−1 in the low pressure (<0.02kPa) as well as the fast response time of 150ms was achieved. The sensitivity was found to primarily vary with the porosity of the elastomer film. Due to the highly elastic and flexible features of the porous film fabricated in a simple way, our pressure sensor is applicable for advanced touch panels with more human-friendly interfaces and skin sensors that allow the detection of a small change in pressure.