In an embodiment, a sensor module 10 includes a piezoelectric element 30 placed on the principal face of a board 20, which piezoelectric element is surrounded by a vibration ring 40 and installed in an appropriate position on a person's arm, neck, etc., using a medical fixing tape, etc., with the vibration ring 40 contacting the person's skin. When a pulse wave is transmitted to the vibration ring 40 from the skin, the board 20 also vibrates and this vibration is transmitted to the piezoelectric element 30. Then, the piezoelectric element 30 is displaced and the pulse wave vibration is converted to an electrical signal. The resulting electrical signal is amplified by an amplifier on the board 20 and input to the vibration analysis device 100, where prescribed calculations are run to perform waveform analysis. The vascular state, etc., can be known from pulse waveforms.