An electrocardiogram analyzer has a measurement section for measuring an electrocardiographic signal; a determination unit for determining, from arrhythmia determination reference information that is information pertinent to arrhythmia, whether or not an electrocardiogram multiplex, which includes a first predetermined number of heart beats, in the thus-measured electrocardiographic signal is arrhythmia; a reference waveform determination unit that determines a reference waveform from the electrocardiogram complex including the first predetermined number of heart beats when the determination unit has determined that the electrocardiogram complex is not arrhythmia, storing the thus determined reference waveform; and an analysis unit that performs an analysis as to whether or not an electrocardiogram complex being measured is arrhythmia by use of the stored reference waveform.