According to the present invention, a moving picture coding apparatus (70) for performing inter-picture predictive coding for pictures constituting a moving picture is provided with a coding unit (103) for performing predictive error coding for image data; a decoding unit (105) for performing predictive error decoding for an output from the coding unit (103); a reference picture memory (117) for holding output data from the decoding unit (105); and a motion vector detection unit (108) for detecting motion vectors on the basis of the decoded image data stored in the memory. When coding a B picture as a target picture, information indicating whether or not the target picture should be used as a reference picture when coding another picture is added as header information. Therefore, in a decoding apparatus for decoding a bit stream Bs outputted from the moving picture coding apparatus (70), management of a memory for holding the reference picture can be facilitated on the basis of the header information.