Abstract Robot manipulators have been applied in the various automated manufacturing for handling, transferring, welding, polishing, painting, deburring, simple assembly and so on. Robotic assembly of the precision parts is difficult because the accuracy of the robot manipulator is not enough and the teaching procedure is complex. There have been various technologies about robotic assembly such as the position based assembly strategy, the active torque feedback control algorithm with FT sensor or joint torque sensors and the remote center compliance which gives the passive compliance to the end-effector. In the paper, we proposed a new type of the passive compliant device which can measure its deformation. The proposed device, which is called “Magic Gripper”, is composed of the passive compliance module, the gripping module, the displacement measurement module and the controller module. Also, a new assembly strategy using the passive compliant device with the displacement measurement system is proposed. The proposed device and the proposed assembly strategy are proved to be very useful for automatic assembly of the precision parts.