1. An apparatus for recognizing an emotion, the apparatus comprising: an input signal generation unit configured to receive a plurality of heart rate data and generate an input signal; a signal classification unit configured to classify prospective input signals into groups; and an emotion recognition unit configured to find a group to which the input signal generated by the input signal generation unit belongs, among the groups classified by the signal classification unit, and recognize a user emotion corresponding to the found group, wherein the input signal generation unit checks whether a current input heart rate differs from a previously input heart rate and represents an increase or a decrease of the current heart rate in the input signal with a binary form sequence.