There is disclosed a decoding method for decoding an incoming bitstream entropy-encoded according to an encoding method based on either of arithmetic encoding algorithm and non-arithmetic encoding algorithm, the incoming bitstream including syntax elements. The decoding method includes a first converting step of converting the incoming bitstream into an intermediate bitstream according to the encoding method, the first converting being capable of being omitted, a buffering step of selecting, according to the encoding method, either the intermediate bitstream or the incoming bitstream to store the selected bitstream onto a memory, and a second converting step of reading the selected bitstream from the memory to convert the read bitstream into syntax elements, the read bitstream being either the intermediate bitstream or the incoming bitstream.