Heart rate monitor and heart rate measuring method

Accurate occurrences of pulsation per unit time, that is, a heart rate is measured with a burden on a subject person being reduced to be very small and without being susceptible to body vibrations accompanying exercise. A heart rate monitor is produced, in which a light-emitting element 11 and a light-receiving element 12 are fitted to a head of a human body, light from the light-emitting element 11 is reflected at or transmitted through a subcutaneous artery 4 and/or blood running in the subcutaneous artery, the reflected or transmitted light is detected at the light-receiving element 12, and by using a CPU 14, the pulsation of the subcutaneous artery 4 and/or a change in bloodstream running in the subcutaneous artery 4 is measured from a change in intensity of the light detected at the light-receiving element 12, a pulse rate of the change in the bloodstream per unit time is calculated from this measured value, and the calculated pulse rate of the change in the bloodstream per unit time is regarded as a heart rate.