To solve the problem that an analysis of the input sequence which is multiplexed on headers of more than one coded data recorded in a storage part is needed conventionally to detect boundary frames in a coding sequence from the boundary frames arranged in the input sequence to an apparatus of moving image coding.

In the apparatus, when performing an advance re-arrangement of video data in a coding sequence, video frames of the coding sequence are acquired from the boundary frames in the input sequence to multiplex flags indicating boundaries on the headers of the video frames arranged in the coding sequence. When reading video frames from a video storing part 3 and outputting it from a multiplexing part 8, the boundary frames in the coding sequence can be detected by detecting the flags multiplexed on the headers.