Orthogonal transform coefficients D6, which are image data of a coded object, are generated by performing predetermined data transform operations on frame image D1 (Step S100), and coded data D7 is generated (S103) by subjecting the orthogonal transform coefficients D6 to arithmetic coding using a predetermined probability table. Then, in variable-length coding for generating the coded data D7, it is set whether or not a probability table is initialized at the slice layer, and a flag indicating the presence of the initialization is added to a header of a predetermined layer. Thus, the image coding method, image decoding method, image coding apparatus, image decoding apparatus, program, computer data signal, and image transmission system, which are capable of enhancing data compression efficiency by coded data in a manner that a probability table is suitably set over the entire coded data, are realized.