A CPU of a blood pressure measurement apparatus configured to be used while attached to a wrist of a measurement subject calculates an inclination angle formed by a forearm of the measurement subject with respect to a reference plane, and a rotation angle about an axis, where the forearm is used as the axis, of the blood pressure measurement device, based on information detected by an acceleration sensor, and uses the distance d between the radial artery and the ulnar artery that pass through the wrist, the inclination angle, and the rotation angle to determine the relative positional relationship between the radial artery and the ulnar artery. In accordance with the relative positional relationship, the CPU guides the measurement orientation of the measurement subject.