PURPOSE: To recognize a resonance frequency securely by detecting a resonance frequency of a resonance circuit of an operation control device at real time.

CONSTITUTION: An operation control device 10 is provided with an input/output control circuit 11, a capacitor 31 for storing loads on the basis of the output of the input/output control circuit 11, a voltage control oscillator 13 for generating the control signal at a continuous frequency in response to the charged voltage of the capacitor 31, a resonance circuit 15 to be driven by the control signal of the voltage control oscillator 13, a comparator 16 for generating the detecting signal when the generation of load fluctuation in the output of the resonance circuit 15 is detected, and a frequency divider 71 for dividing the output of the voltage control oscillator 13 and for supplying it to the input/ output control circuit 11. When the input/output control circuit 11 receives the detecting signal of the comparator 16, the input/output control circuit 11 detects the resonance frequency of the resonance circuit 15 on the basis of the output of the frequency divider 17, and when the resonance circuit 15 is resonated at a predetermined frequency, the input/output control circuit 11 supplies the operating signal to a material 17 to be controlled.