Provided are an audio data encoding method and apparatus including determining an initial scale factor value for each frequency band of the audio data according to a quantization error and a maximum permissible distortion level for each frequency band; comparing the initial scale factor value for each frequency band and a predetermined common scale factor value and determining a final scale factor value for each frequency band based on a comparison result; quantizing the audio data using the final scale factor value for each frequency band; and encoding the quantized audio data.