A moving image encoder has an image separating unit (1) for generating four separate images (1)-(4) by sampling pixels constituting an input image every two alternate pixels in the horizontal direction and each alternate pixel in the vertical direction. An intraframe predictive coding unit performs intraframe predictive coding of the separate image (1) by using pixels constituting the separate image (1) produced by the image separating unit (1). An inter-separate image predictive coding unit 12 performs inter-separate image predictive coding of the separate images (2)-(4) produced by the image separating unit 1 by using the pixels constituting the separate image (1) produced by the image separating unit (1).