A blood pressure monitor that includes an acceleration sensor attached to an arm, which is a measurement site, of a measurement subject, and an orientation detection unit that detects an orientation of the measurement subject during blood pressure measurement based on an output of the acceleration sensor. The orientation detection unit specifies the orientation of the measurement subject in accordance with a torso angle with respect to a bed surface in a view along a body height direction of the measurement subject lying on the bed surface, and the orientation of the arm position. The blood pressure monitor also includes a blood pressure measurement unit that measures a blood pressure value at the measurement site of the measurement subject, and a blood pressure correction unit that corrects the blood pressure value of the measurement subject according to the specified orientation of the measurement subject.