A vagus nerve is efficiently stimulated while preventing wasteful energy consumption. Provided is a nerve stimulating device (1) including a stimulation-signal outputting portion (3) that outputs a stimulation signal to a vagus nerve (B); a heart-event detecting portion (2) that detects a heart event; and a control portion (4) that makes a judgment regarding the responsiveness of a heart (A) based on the heart event detected by the heart-event detecting portion (2) in response to the stimulation signal output from the stimulation-signal outputting portion (3), and that controls the stimulation-signal outputting portion (3) so that an intensity of the stimulation signal is decreased when the responsiveness of the heart (A) is decreased.