This paper presents a new mechanism for excitation of ultrasonic vibration in a metal ring. Four pairs of piezoelectric elements were embedded in four arcuate metal blocks and configured an annular vibration system. The proposed method is effective for compact and high power ultrasonic system design, and for excitation of two degenerate vibration modes spatially and temporally orthogonal to each other to produce the traveling wave. The system, composed of 20-mm diameter piezoelectric ceramic disks for torsional vibration embedded in four 140-mm diameter aluminum blocks, was designed via finite element analysis to operate using out-of-plane vibration modes and their traveling waves, and the expected motions were confirmed theoretically.