A blood pressure measuring apparatus comprising: a cuff configured to be mounted to a region of a living body in which a vein and an artery exist; a pressure control unit configured to control an applied pressure applied to the region by the cuff mounted to the region; a detection unit configured to detect pressure waveforms in which pulse wave components from the region overlap with the applied pressure; and an analysis unit configured to obtain an arterial pressure, a respiratory variation on the waveform of artery and a venous pressure based on the pressure waveforms detected by the detection unit through one-time blood pressure measurement, wherein the analysis unit is configured to obtain: the respiratory variation on the waveform of artery based on data of a first pressure waveform of the pressure waveforms in a first process, in which the applied pressure is kept at a constant pressure by the pressure control unit; the venous pressure based on data of a second pressure waveform of the pressure waveforms in a second process in which the applied pressure is decreased or increased by the pressure control unit; and the arterial pressure based on data of a third pressure waveform of the pressure waveforms in a third process in which the applied pressure is decreased or increased by the pressure control unit, and wherein the first, second and third processes for obtaining respectively the respiratory variation, the venous pressure, and the arterial pressure are completed in about 140 seconds. a cuff configured to be mounted to a region of a living body in which a vein and an artery exist; a pressure control unit configured to control an applied pressure applied to the region by the cuff mounted to the region; a detection unit configured to detect pressure waveforms in which pulse wave components from the region overlap with the applied pressure; and an analysis unit configured to obtain an arterial pressure, a respiratory variation on the waveform of artery and a venous pressure based on the pressure waveforms detected by the detection unit through one-time blood pressure measurement, wherein the analysis unit is configured to obtain: the respiratory variation on the waveform of artery based on data of a first pressure waveform of the pressure waveforms in a first process, in which the applied pressure is kept at a constant pressure by the pressure control unit; the venous pressure based on data of a second pressure waveform of the pressure waveforms in a second process in which the applied pressure is decreased or increased by the pressure control unit; and the arterial pressure based on data of a third pressure waveform of the pressure waveforms in a third process in which the applied pressure is decreased or increased by the pressure control unit, and the respiratory variation on the waveform of artery based on data of a first pressure waveform of the pressure waveforms in a first process, in which the applied pressure is kept at a constant pressure by the pressure control unit; the venous pressure based on data of a second pressure waveform of the pressure waveforms in a second process in which the applied pressure is decreased or increased by the pressure control unit; and the arterial pressure based on data of a third pressure waveform of the pressure waveforms in a third process in which the applied pressure is decreased or increased by the pressure control unit, and wherein the first, second and third processes for obtaining respectively the respiratory variation, the venous pressure, and the arterial pressure are completed in about 140 seconds.