Abstract: Disclosed are a vascular disease examination system capable of examining and diagnosing vascular diseases such as arterial obliteration by determining the feature quantities of blood flow velocity waveforms or blood pressure waveforms or blood flow rates, and a bypass vascular diagnosing system. A blood flow velocity or blood pressure at a target location of the body is measured A waveform analysis unit 4 determines the feature quantity of a blood flow waveform (or blood pressure waveform), for displaying on an output unit 5. The feature quantity includes a time constant, Fourier transform value, differentiated value, integrated value, rise/fall time, and sharpness or gradient of rise. Feature quantity of a blood flow velocity waveform (or blood pressure waveform) indicated in numeric value enables a correct examination/diagnosis.