A swing analyzer is disclosed. The swing analyzer may be used to analyze the swing an object such as a golf club. The swing analyzer accounts for individual differences between users and/or sensors to improve performance. The swing analyzer includes a motion sensor that is attachable to the object. The motion sensor communicates wirelessly with a terminal device. The terminal device includes a swing analysis unit for performing swing analysis based on sensor data output from the motion sensor. The swing analyzer determines a target line based on position of the motion sensor while a user is at the address posture before a swing. The target line is used as a reference to provide swing analysis.