A moving image encoding/decoding system may include a video predictive encoding device, which may include: an encoding device which encodes each of a plurality of input pictures to generate compressed picture data including a random access picture, and encodes data about display order information of each picture; a restoration device which decodes the compressed picture data to restore a reproduced picture; a picture storage device which stores the reproduced picture as a reference picture; and a memory management device which controls the picture storage device. Following completion of an encoding process of generating the random access picture, the memory management device refreshes the picture storage device by setting every reference picture in the picture storage device, except for the random access picture, as unnecessary immediately before or immediately after encoding a picture with display order information larger than the display order information of the random access picture.