Background, Motivation and Objective Ultrasonic welding could not been applied for deep and narrow parts positioned at long distance from the vibration system. Usually, electric resistance or laser welding was used to weld such part, but there are possible fatal defect caused by sparked metal particles. To join such deep area, ultrasonic complex vibration system using small diameter long welding tip were developed. Using ultrasonic complex vibration with circular to elliptical vibration locus, required vibration amplitude, and static pressure decreased significantly due to two-dimensional vibration stress. To improve welding characteristics furthermore, complex vibration velocity detector of welding tip and static pressure control system were developed.