A moving picture coding apparatus for performing inter-picture prediction coding on a picture constituting a moving picture includes a coding unit for performing prediction error coding on image data, a decoding unit for performing prediction error decoding on the output of the coding unit, a reference picture memory for storing output data from the decoding unit, and a motion vector detector for detecting a motion vector according to the decoded image data stored in the memory. When coding a B picture as a coding object picture, information indicating whether the coding object picture is used as a reference picture upon coding of another picture is added as header information. In a decoding apparatus for decoding a code string Bs output from the moving picture coding apparatus, it is possible to simplify management of a memory for storing reference pictures according to the aforementioned header information. |