PROBLEM TO BE SOLVED: To measure biological information without affecting music reproduction or a call, by use of an existing terminal device.SOLUTION: A biological information measurement system includes: a terminal device having analog sound output function and analog sound input function and a headset having a sound reproducing unit which is connected by wire to the terminal device via an analog sound output terminal and an analog sound input terminal, to reproduce sound on receipt of an analog output sound signal from the terminal device. The headset includes: a sensor for acquiring biological information of a person with the headset mounted thereon and a controller which extracts a sensor driving signal included in the analog output sound signal from the terminal device, to drive the sensor, and transmits the biological information acquired by the sensor, to the terminal, by superimposing it on an analog input sound signal. The terminal device includes an information processing section which outputs the sensor driving signal superimposed on the analog output sound signal and extracts the biological information superimposed on the analog input sound signal, to be processed.SELECTED DRAWING: Figure 1
