The present invention inexpensively provides a biological information acquisition device that can accurately measure biological signals without interfering with daily life. A biological information acquisition device 1 acquires biological information about a subject H1 and comprises a pair of measurement pad parts 3 that can measure biological signals and a body frame 2 that presses the measurement pad parts 3 toward each other onto the backs of the base of the ears E1 of the subject H1 with equal urging force. A biological signal processing unit 4 is connected to the measurement pad parts 3. The biological signal processing unit 4 performs computation processing on the biological signals measured by the measurement pad parts 3 and extracts biological information.