The present technology relates to an encoding device and method, a decoding device and method, capable of improving audio signal transmission efficiency. An identification information generation unit determines whether or not an audio signal is to be encoded on the basis of the audio signal. The identification information generation unit generates identification information indicating the determination result. An encoding unit encodes only the audio signals which are determined to be encoded. A packing unit generates a bit stream containing the identification information and encoded audio signals. As a result of storing only encoded audio signals and the identification information indicating whether or not the respective audio signals are to be encoded in the bit stream, the transmission efficiency of the audio signals can be improved. The present technology can be applied to an encoder and a decoder.