There are provided a moving image coding apparatus and moving image decoding apparatus which allow efficient decoding of an interlaced image from the coded data of a progressive image, and methods for the apparatuses. Noninterlaced moving image data is input from a moving image data input unit (101). Two consecutive frames are discriminated by a switch (102). A line interleaving unit (103) then generates new image data by alternately arranging the line data of the respective frames upon changing the order. A discrete wavelet transform unit (104) performs two-dimensional discrete wavelet transform for this image data to decompose it into seven subbands. Each subband is then coded.