1. A scalable moving image encoder comprising: a pixel value clipper which clips a pixel value of an original image to a pixel value having a predetermined pixel depth; a base layer encoder which receives a clipped image and encodes the clipped image using a first predetermined encoding method based on motion prediction; a pixel value scaler which receives a base layer image generated by the base layer encoder, which is a decoded image of an encoded image, and scaling a pixel depth of the base layer image to a pixel depth of the original image; and an enhancement layer encoder which subtracts the base layer image having a scaled pixel value from the original image to produce an enhancement layer image and encodes the enhancement layer image using a second predetermined encoding method, wherein the enhancement layer encoder comprises a motion estimator and a motion compensator, and the second predetermined encoding method used to encode the enhancement layer image is based on another motion prediction.