A CPU of a sphygmomanometer includes a first control unit that, during measurement, controls a change in the internal pressure of a measurement air bladder by controlling the driving of a pump and/or a valve. The CPU further includes a second control unit that controls a change in the internal pressure of a compressing air bladder by controlling the driving of a pump and/or a valve. During measurement, the second control unit carries out control so that the internal pressure of the compressing air bladder is a predetermined ratio to the internal pressure of the measurement air bladder controlled by the first control unit.