A sphygmomanometer, in a deflation process after inflation to prescribed pressure adjusts a drive voltage of an exhaust valve such that a deflation speed of a fluid bag achieves a prescribed deflation speed during an adjustment period, which is a prescribed period after starting deflation. When the adjustment period ends or when the deflation speed of the fluid bag achieves the prescribed speed, control is subsequently performed to fix the drive voltage of the exhaust valve and deflate the fluid bag while holding a gap of the exhaust valve constant.
