Provided is a method and apparatus for encoding a scalable wideband audio signal, the method including: filtering a voiced signal by performing linear prediction on the voiced signal and modulating the filtered signal; encoding the modulated signal in the time domain, and outputting a core layer encoding result of the voiced signal; subtracting a signal obtained by decoding the core layer encoding result from the modulated signal and outputting an error signal; and encoding the error signal and outputting an enhancement layer encoding result of the voiced signal.