A micropositioning system for automatic precision assembly is introduced. The proposed precision assembly system is aimed at automation of precision assembly of precision optical or magnetic components, which was previously performed by specially trained technicians. The positioning system is based on the motion mechanism driven by impact force made by piezoelectric actuator; it utilizes dry friction and impulsive inertial force. The motion mechanism consists of the main body, a piezoelectric actuator, and a weight. The motion mechanism can make minute motion of several nanometer and has an unlimited movable range at the same time. The proposed assembly system uses the motion mechanism as a source of impact force. The motion mechanism is proved to have the advantage of positioning resolution, range, and flexibility. An industrial application of this device is also presented.