A method and apparatus that, when generating a multimedia file in which encoded data management information is placed at the head of the file, estimates the size needed for the management information in advance and generates a file in which an empty space the size of the estimated size is reserved at the head of the file, with the encoded data directly recorded behind the empty space. If the reserved empty space is insufficient, a new file that reserves a larger empty space is generated and the recorded encoded data is copied and the management information that is ultimately generated is inserted in the head of the file, thus shortening contents creation time and moreover reducing storage space for multimedia contents designed for quick reproduction.