A vehicle behavior detector obtains detection information from autonomous sensors to detect a change in vehicle behavior. The detection information is calibrated based on position, bearing, and vehicle speed information obtained from a GPS receiver. For example, the vehicle behavior detector calibrates detection information obtained from the vehicle speed sensor and the angular speed sensor with a Kalman filter process. It is difficult to use only the autonomous sensors to calibrate characteristics changes due to individual sensor differences, environmental changes, and aged deterioration. With using GPS information for calibration, the vehicle behavior detector can accurately detect the vehicle behavior. The accuracy is improved for detection information itself to be output from the vehicle behavior detector to external apparatuses. Using this calibrated detection information, the external apparatuses can perform processes appropriately.