To improve measurement accuracy of blood pressure. A wrist sphygmomanometer (10) comprises a cuff spring (13) formed in a curved shape to fit the semicircle on the side of the pulsation part of the wrist, having a mount portion (22) formed outside a cuff band (12) including the cuff spring as a core material, having an air bag (19) inside, and wound around a wrist and a sphygmomanometer main body (11) mounted on the mount portion of the cuff spring, having a pressure pump for supplying air to the air bag, wherein the cuff spring has a protrusion (26) protruding inward formed in a nearly central position in a peripheral direction.
