An LSI device for decoding a coded image segmented and coded in a plurality of blocks. The LSI device includes a section which receives a filter selection parameter that determines a threshold value for each quantization parameter, for changing between conducting and non-conducting a coding distortion removal by the use of a filter. A decoder, decodes a coded block to obtain a reproduced image. A remover, removes a coding distortion from a region including both sides of a block boundary between adjacent decoded blocks that form the reproduced image, in accordance with a comparison of a difference value of the pixels in adjacent decoded blocks with the threshold value determined based on the filter selection parameter, such that the coding distortion removal is not conducted when the difference value is greater than the threshold value. The coding distortion removal is conducted by the use of the filter when the difference value is smaller than the threshold value.