A conversion control unit divides a transform coefficient into code blocks. A storing device has a storage capacity corresponding to data size of the code blocks. To the conversion control unit, rotation/inversion control information including information of the rotation angle and the inverting direction is input. The conversion control unit generates a control signal on the basis of the rotation/inversion control information and sub-band information of the transform coefficient. An address generating unit generates a write address on the basis of a control signal. By accessing the storing device in predetermined order on the basis of the write address at the time of writing the code block to the storing device, an image rotating/inverting process is performed.