Provided is an ultrasonic vibration device, wherein a vibration area (VA) is formed by a recess section (40) having an approximately ellipse shape with a major axis and a minor axis, at the inner bottom face of a case (31). A piezoelectric element (37) is adhered to the center of the recess section (40). Vibration alleviation areas (SVA) having a thickness greater than the vibration area (VA) are arranged at both sides of the vibration area (VA). The side section of the case (31) is formed to be thin-walled around the whole circumference thereof. A reinforcement member (41) having a higher rigidity than the case (31) is adhered to the upper part of the vibration alleviation areas (SVA). The reinforcement member (41) has bottom faces shaped approximately the same as the vibration alleviation areas (SVA), and has a prescribed height. Filler (35) is filled into the gap between the reinforcement member (41) and the inner side face of the case (31).