A blood pressure monitor includes a cuff and main unit. The cuff includes a fluid bladder, tube, and approximately cylindrical plug attached to a leading end of the tube, and a through-hole is provided in peripheral wall of plug. An inner diameter of a part of plug further on leading end side of plug than through-hole is set variably, in accordance with the type of cuff, to a diameter ≦ inner diameter of a part of plug aside from part further on leading end side. Main unit includes a plug receiving portion that communicates with pump via a pipe, a first pressure sensor that detects pressure in pipe, second pressure sensor that detects an inner pressure of plug inserted into plug receiving portion, and cuff type determining unit that determines type of cuff connected to main unit on basis of difference between pressures detected by first and second pressure sensor.
