PURPOSE: To provide a method for measuring accurately and speedily the circuit parameter of an element whose frequency characteristics need to be adjusted.

CONSTITUTION: The device 1 for measuring the circuit parameter of an element 7 to be measured according to a measurement signal and the output signal of an element 7 to be measured by applying the measurement signal from a signal source 2 to the element 7 to be measured is provided with a function for controlling so that a measured value is nearly equal to a given value and a function for controlling so that a measured value is nearly equal to an extreme by changing the output frequency of the signal source 2 by adding a frequency following algorithm 17 to an operation control part 19.