Heart rate monitor and heart rate measuring method

1. Field of the Invention 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 and a light-receiving element are fitted to a head of a human body, light from the light-emitting element is reflected at or transmitted through a subcutaneous artery and/or blood running in the subcutaneous artery, the reflected or transmitted light is detected at the light-receiving element , and by using a CPU , the pulsation of the subcutaneous artery and/or a change in bloodstream running in the subcutaneous artery is measured from a change in intensity of the light detected at the light-receiving element , 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.