A blood pressure monitor includes a processor configured to control a cuff pressure and calculate blood pressure information of a subject based on a cuff pressure signal representing the cuff pressure and a pulse wave signal superimposed on the cuff pressure signal. The processor calculates first blood pressure information of the subject who has maintained a recumbent position for a prescribed time period, maintains the cuff pressure at a first pressure lower by a prescribed value than a systolic blood pressure included in the first blood pressure information, determines if an amplitude of the pulse wave signal is equal to or greater than a threshold value when the cuff pressure is maintained at the first pressure and the subject is in an upright position, assesses an autonomic nerve function of the subject based on a result of the determination, and outputs a result of the assessment.