To speedily provide a highly reliable inspection result by previously memorizing corresponding relations between a control constant and an output signal, carrying out measurement by selecting the control constant to be inspected when a starting signal is output and outputting and displaying it as the output signal based on a corresponding list from its measured result.

It is frunished with a first corresponding list memory means 12 to previously memorize a corresponding list to show corresponding relations between a value free to select of a control constant and a value free to select of a control constant of initial opening and an output signal, a startin condition output means 21 to output a signal to start an inspection program, a control constant selection means 16 to select a kind of the control constant to inspect in accordance with the kind of the signal sent from a vehicle after receiving the output signal, a first control constant measuring means 17 to measure the selected control constant, a first measured result output means 18 to output the output signal corresponding to a measured value in accordance with the first corresponding list and a first output signal display means 22 to receive the output signal and to display its contents.