An image decoding apparatus is capable of decoding coded bit streams with different coding schemes. The image decoding apparatus includes a coding scheme decision section for deciding a coding scheme from coding scheme identification information multiplexed into a coded bit stream, a setting unit for setting header information on a second coding scheme in accordance with header information in a first coding scheme, and a decoder for decoding image coded data in the first coding scheme in response to the header information on the second coding scheme, which is set.