PURPOSE: To improve the job efficiency and measuring accuracy by using a local oscillation circuit of a tuner to be measured as a common reference oscillation source so as to make the tuning coincident with the tuner to be measured in terms of frequencies completely.

CONSTITUTION: A local oscillating frequency detected from a reception frequency selection local oscillation circuit of a tuner 1 to be measured is converted into a frequency to be received at that time and the result is used for an input frequency of the tuner 1. Thus, the frequency of the tuner 1 to be received is tuned always to the frequency (output of a characteristic measuring device) of the frequency inputted to the tuner 1, since the input matching ratio characteristic of the normal tuning point (in this case, video signal) of the tuner 1 is always measured without being affected by the variable speed by having only to vary the local oscillation frequency of the tuner 1 to be measured, the measuring time is reduced remarkably to improve the measuring efficiency. Since the tuning is taken completely, the measuring accuracy is improved.