In encoding of moving pictures, I-frame is inserted when a scene change occurs. If scene changes frequently occur in the range of a predetermined amount-of-information allocation, the amount of information allocated to an encoding process on I-frame becomes enlarged. Therefore, the amount of information cannot be sufficiently reserved for another coding, thereby considerably degrading the quality of an image. Thus, a scene change detection threshold is obtained depending on the remainder in the VBV buffer, the scene change detection threshold is compared with a scene change detection value for determination of the occurrence of a scene change, and it is determined whether or not a scene change has occurred based on the comparison result.