A biological property check device includes a plurality of probes (20) each having a light emitting element (26) for applying light to a biological tissue and a light reception element (28) for detecting the reflected light. Each probe (20) is successively selected by a switch circuit (60) under control of a control section (76) and connected to a property calculation section (64). The property calculation section (64) includes a phase shift circuit for changing the frequency according to the phase difference between the input waveform to the light emitting element (26) and the output waveform from the light reception element (28). According to the frequency change, the property of the biological tissue is calculated. The property calculated is displayed on a display section (74) via a data collection section (70) and a display processing section (72).