A heart rate meter includes a heart beat detecting unit for detecting a heart beat waveform of a living body and a signal processor 4 for detecting a heart beat from the heart beat waveform. The signal processor 4 includes a heart beat signal generating processor 5 for adding a predetermined frequency characteristic to the signal within a predetermined narrow band of the heart beat waveform to generate a heart beat signal, and a heart beat detecting processor 6 for detecting a heart beat from a waveform distortion that is added to the heart beat signal by the heart beat signal generating processor. The heart beat signal generating processor 5 subjects the signal within the predetermined narrow band of the heart beat waveform to a signal processing, thereby removing the noise component existing in the frequency band, other than the primary component of the heart beat waveform, and performs signal processing to add the predetermined frequency characteristic, thereby generating a heart beat signal in which the signal intensity of a frequency component is amplified. The heart beat detecting processor 6 detects the waveform distortion added to the heart beat signal by the heart beat signal generating processor. Even when there is a variation in the measuring condition and signal characteristics such as the frequencies and the crest values of the fundamental wave, higher harmonic, and noise component are changed, a heart beat is accurately detected.