A harmony generation device and a program for the same which can generate a natural harmony sound are provided. The harmony generation device (1) generates first and second harmony tones to which a voice input through a microphone (M) is shifted in pitch by first and second shift amounts calculated based on both the voice input through the microphone (M) and a chord determined from performance information of an electric guitar (G) input through an input device (34). That is, since the first and second harmony tones can be tones based on the chord of the electric guitar (G) that changes from moment to moment, the harmony sound obtained by mixing the first and second harmony tones with the voice input through the microphone (M) can be a natural harmony sound that is rich in variation according to the chord of the electric guitar (G).