A heartbeat detection device includes a peak search unit (4) for searching for one of a peak at which a value M obtained from a sampling data sequence of an electrocardiographic waveform of a living body changes from an increase to a decrease and a peak at which the value M changes from a decrease to an increase, and a heartbeat time determination unit (5) for checking the value M in a predetermined time domain before a time of the peak and the value M in a predetermined time domain after the time of the peak, and setting the time of the peak as a heartbeat time if differences between the value M at the time of the peak and the values M in the predetermined time domains are not smaller than a predetermined amount.