There is disclosed a speech switching device capable of improving quality of a decoded signal. In the device, a weighted addition unit outputs a mixed signal of a narrow-band speech signal and a wide-band speech signal when switching the speech signal band. A mixing unit formed by an extended layer decoded speech amplifier and an adder mixes the narrow-band speech signal with the wide-band speech signal while changing the mixing ratio of the narrow-band speech signal and the wide-band speech signal as the time elapses, thereby obtaining a mixed signal. An extended layer decoded speech gain controller variably sets the degree of change of the mixing ratio by the time.