This paper reports on a tactile sensor to measure normal force, tangential force and friction coefficient simultaneously. The proposed sensor is composed of three pairs of piezoresistive beams embedded in an elastomer. The normal and tangential forces can be measured by detecting the normal and shear deformations of the elastomer with the piezoresistive beams. The friction coefficient can be measured by calculating the ratio of the extension of the elastomer to the normal force. We demonstrated that the normal force from 0 to 8 N and the tangential force from 0 to 0.8 N were able to be measured independently by using the fabricated sensor. Moreover, we found that the ratio of the outputs from the piezoresistors was independent of the applied forces, and varied with the coefficients of static friction from 0.2 to 1.5.