To provide a biological information measuring device which can measure a subject for a long period of time without feeling discomfort in a research for ergonomics and a clinical diagnosis.

This biological information measuring device for detecting biological information on the subject includes a head set fixed to the subject's head in a substantially semicircular state, a tube fixed on the head set, and a thermocouple inserted into the tube and exposing a sensor at the tip of the tube and disposed near the subject's nasal cavity. A change in temperature due to subject's respiration is measured by the thermocouple, and information regarding the subject's respiration is detected as the biological information.