A sphygmomanometer of the present invention includes a bag-shaped sensing cuff to be worn to wrap a measurement site, a back plate disposed on the sensing cuff along a surface opposite to the measurement site, a pressing member for pressing the back plate toward the measurement site, and a blood-pressure calculating part calculating a blood pressure based on a pressure of a fluid stored in the sensing cuff. Regarding a longitudinal direction perpendicular to a circumferential direction of the measurement site to be wrapped by the sensing cuff, a dimension of the back plate in a width direction along the longitudinal direction is larger than a dimension of the sensing cuff in the width direction.
