A disclosed speech sound enhancement device includes an SNR calculation unit for calculating an SNR which is a ratio of received speech sound to ambient noise; a first-frequency-range enhancement magnitude calculation unit for calculating, based on the SNR and frequency-range division information indicating a first and a second frequency range, enhancement magnitude of the first frequency range, the first frequency range contributing to an improvement of subjective intelligibility of the received speech sound, the second frequency range contributing to an improvement of subjective articulation of the received speech sound; a second-frequency-range enhancement magnitude calculation unit for calculating enhancement magnitude of the second frequency range based on the enhancement magnitude of the first frequency range; and a spectrum processing unit for processing spectra of the received speech sound using the enhancement magnitude of the first frequency range, the enhancement magnitude of the second frequency range and the frequency-range division information.