Heart sound extraction device, heart sound extraction program, recording medium, and monitoring system

In the present invention, a heart sound extraction device (3) is provided with: an acquisition unit (31) that continuously acquires a piezoelectric signal output from a sheet-shaped sensor, when an individual lies on the sheet-shaped sensor that outputs the piezoelectric signal in accordance with an applied vibration; a heart sound signal extraction unit 32c for extracting a heart sound signal of the individual from the piezoelectric signal; and a time window setting unit (32g) that sets, in the extracted heart sound signal, at least one of (1) a time window in which the reciprocal of the standard deviation of the respiratory rate is the maximum or equal to or greater than a predetermined value, (2) a time window in which the periodic respiratory power is the maximum or equal to or greater than a predetermined value, and (3) a time window in which the periodic respiratory power is the maximum or equal to or greater than a predetermined value. (3) a time window in which the heart sound signal amplitude is maxi