A method, medium, and apparatus for measuring a heart rate from blood flow in a blood vessel of a human body part, including: an amplifying circuit receiving a light signal reflected or penetrated from a human body part and generating a multi-stage amplified signal made up of a plurality of signals with a corresponding different gains and a processor separating the multi-stage amplified signal into a plurality of channel signals having corresponding gains, reconfiguring the light signal using a channel signal selected among the plurality of channel signals and calculating the heart rate from the reconfigured light signal. Accordingly, it is possible to make an accurate measurement of a heart rate by minimizing effects of measuring environments. In addition, the apparatus, method, and medium are resistive to noise resulting from a movement of a human body part by comparing an optimum signal pattern and a correlation coefficient.
