1. A sphygmomanometer, comprising: pressurizing means for applying variable pressure to a blood vessel; oscillation detecting means for detecting oscillation produced from the blood vessel while pressurized by said pressurizing means; pressure sensing means for sensing pressure being applied to the blood vessel; Korotkoff sound recognizing means for recognizing Korotkoff sounds out of the oscillation detected by said oscillation detecting means; blood pressure computing means for computing blood pressure from the pressure applied to the blood vessel as detected by said pressure detecting means when said Korotkoff sound recognizing means has recognized one of the Korotkoff sounds; and time width setting means for setting a delay period of time based on the amplitude of a most recent one of the Korotkoff sounds recognized by said Korotkoff sound recognizing means and for inhibiting an output from said oscillation detecting means to said Korotkoff sound recognizing means during the delay period, thereby said Korotkoff sound recognizing means being unable to recognize any of the Korotkoff sounds until the delay period of time set by said time width setting means expires.