This biological information measurement device comprises: a fluid bag; a pump; a valve; a blood pressure measurement unit that measures the blood pressure; a first electrode that comes into contact with a first part of a subject; a second electrode that comes into contact with a second part, the second electrode being connected to the fluid bag, supported by a support member that extends farther in the circumferential direction from the circumferential end of the fluid bag, and positioned a predetermined distance away from the end in the circumferential direction; an electrocardiogram measurement unit that measures an electrocardiogram waveform of the subject; a belt part that is wrapped around the outer circumference of the fluid bag; and a contact state stabilizer for suppressing a change in the state of contact of the second electrode with respect to the second part due to a change in volume of the fluid bag.