Provided is a method of monitoring a heart rate of an open circulatory system aquatic organism including water fleas, zebrafish, brine shrimp, and the method of evaluating individual response by real time measurement of a heart rate of an aquatic organism and the individual response evaluation apparatus by real time measurement of a heart rate of an aquatic organism according to the present invention may effectively fix the aquatic organism for real time measurement of the heart rate of an aquatic organism, and may measure the heart rate using digital holography to display the heart rate while configuring a data format to allow the corresponding data to be stored for a long time, thereby treating a compound for inducing an individual response, securing a heart rate change in real time by image processing, and then effectively determining the presence or absence of harmfulness due to induction of the individual response.