For the post-operative treatment of the prosthetic cardiac valve, its closure click was measured clinically. Ultrasonic range signal components, as well as the widely known audible signal components were found to exist. The frequency range of the ultrasonic click was from 8 kHz to more than 600 kHz, while that of the audible click was up to 8 kHz. Both of the clicks included effective diagnostic information. The Wigner distribution (WD) of the audible closing click offered the possible indices of thrombus and/or sclerosis. Especially, the first-order local moment of the WD showed capability for the quantitative diagnosis of the thrombosed valve. The ultrasonic closing click offered more diagnostic information for the bileaflet valve, while it also had sensitivity for the thrombosed valve. Since the waveform of the ultrasonic click indicated clearly the instance of the valve closing, it also revealed the exact time difference between the closing time of each leaflet, which could be used as the indices of bileaflet valve malfunction. With those characteristics of the closing click, detailed diagnosis of the prosthetic cardiac valve malfunction could be determined.