To achieve the control and operation optimum for each occupant based on the information by determining the start of an occupant crash protection device optimizing program by an on-vehicle computer based on the result judged by an identification part to identify the information.

A finger print sensor 1' is integratedly provided on a tongue 7 of a seat belt 5. The tongue 7 is supported by a right hand when the seat belt 5 is fitted, and inserted in a buckle 3 of the seat belt in a left hand. A shallow recess 13 where an index finger can be placed is formed in a surface of the tongue 7, and the finger print of the index finger is detected. Thus, the finger print can be detected simultaneously with the action to fit the seat belt. An individual can surely be recognized by using a device to recognize the finger print specific to the individual. In addition, the autonomous action need not be forced to the occupant by fitting this finger print recognizing device to the buckle, the tongue, etc., with which the finger is essentially brought into contact in fitting the seat belt.