An apparatus for determining a possibility of return of spontaneous circulation, includes: an electrocardiogram acquiring unit acquiring electrocardiogram waveform data from a subject in a cardiac arrest condition during chest compression applied to the subject； a bandpass filter unit allowing only a frequency component in a vicinity of a frequency of a P wave of the electrocardiogram waveform to pass through the bandpass filter unit； a resuscitation possibility determining unit determining whether an output of the bandpass filter unit exceeds a predetermined value or not, and determining that there is the possibility of return of spontaneous circulation when the output exceeds the predetermined value； and an outputting unit outputting a result of determination related to the possibility of return of spontaneous circulation.
