THEFT PREVENTING DEVICE FOR VEHICLE

PROBLEM TO BE SOLVED: To make an engine control program rapidly function by constituting to obtain the same ID code continuously a plurality of times for collation by the output of one ID code request signal. SOLUTION: An ID code request signal generating means of a CPU 25 supplies an ID code request signal to an antenna coil 22 immediately after supplying a switch signal to the CPU 25 from an ignition switch 24. A control means reads a registered ID code from an EEPROM 26 immediately after the output of the ID code request signal from the CPU 25 and further reads an ID code Y which is reply data supplied from a transponder 21, and collates both read ID codes to judge whether they are coincident. When they are coincident, collation with a following received ID code is not performed, and collation with the following supplied ID code is performed only when they are not coincident.