Provided are an ultrasonic actuator and a method for manufacturing an piezoelectric deformation portion in which wiring a drive circuit can be easily processed, and in which productivity can be increased. The ultrasonic actuator comprises: a triangular vibrating member which has a piezoelectric deformation portion which is deformed by driving signals; a moving member that is pressure-contacted to at least one of the vertices of the vibrating member and generates a movement relative to the vibrating member; and a plurality of external electrodes integrally provided on one side surface of the vibrating member; wherein the piezoelectric deformation portion is formed by alternately laminating piezoelectric layers made of piezoelectric material and internal electrode layers including internal electrodes, and the plurality of external electrodes interconnect the internal electrodes in a prescribed combination.