To prevent a high-frequency receiver from deteriorating in S/N by setting an operation clack frequency, so as not to make the operation clock frequency and the frequency of the multiple to be present inside the broadcasting band of the high-frequency receiver.

A CPU requires clocks for an operation so as to synchronize an arithmetic processing, a ROM and a RAM, an oscillation circuit 12 is provided on the outside of the CPU, and clock signals are supplied to the CPU, the ROM and the RAM. Then frequencies pertinent to the fundamental wave component of the clock signals and the multiple of fundamental waves match the reception frequency band of the high-frequency receiver present inside the same vehicle, they are injected to the receivers as clock noise signals. Thus, setting is performed so as to make the frequencies equivalent to the fundamental wave of the operation clock frequency of this electronic control, and the multiples of the fundamental waves avoid the respective frequency bands of the high-frequency receiver present inside the same vehicle compartment. Thus, the need for noise investigation normally performed by the electronic controller is eliminated.