A biological information measurement device measuring blood pressure of a subject and biological information which includes: a curved support member; a belt portion; a fluid bag; a pump; a valve; a blood pressure measurement unit; a detection unit which comes into contact with the measurement site of the subject; and a biological information measurement unit measuring the biological information with the detection unit, in which the fluid bag includes a first bag portion and a second bag portion, and the detection unit which is arranged at a position which allows a change in a contact state between the detection unit and the measurement target site due to movement of the detection unit support portion accompanying a volume change of the fluid bag and the second bag portion to be limited to a predetermined range.