An image coding apparatus configured to code an image into a bit stream, the image including one or more slices, each slice including a plurality of blocks, the image coding apparatus comprising: first coding means for coding blocks included in a first block line of the slice in an order starting from a first block which is a left-most block of the first block line, said first block line comprising a plurality of blocks arranged in a horizontal direction in the image, wherein the first coding means is arranged to code the blocks included in the first block line by using arithmetic coding, and wherein the first coding means is arranged to update statistical information for arithmetic coding when coding the blocks included in the first block line; and second coding means for coding blocks included in a second block line of the slice in an order starting from a first block which is a left-most block of the second block line, said second block line comprising a plurality of blocks arranged in a horizontal direction in the image, wherein the second coding means is arranged to code the blocks included in the second block line by using arithmetic coding, and wherein when coding the first block of the second block line, the second coding means is arranged to use the statistical information updated when a predetermined block of the first block line is coded, wherein, the first coding means is arranged to code, for a quantization parameter of the first block in the order of coding the blocks included in the first block line, a difference value between the quantization parameter of the first block included in the first block line and a slice quantization parameter that is provided to the slice as an initial value, the second coding means is arranged to code, for a quantization parameter of the first block in the order of coding the blocks included in the second block line, a difference value between the quantization parameter of the first block included in the second block line and the slice quantization parameter that is used by the first coding means when coding the quantization parameter of the first block of the first block line, and quantization parameters of subsequent blocks of the first block of the first block line and quantization parameters of subsequent blocks of the first block of the second block line are coded by using the quantization parameter of a preceding block of the respective block line according to the order of coding. first coding means for coding blocks included in a first block line of the slice in an order starting from a first block which is a left-most block of the first block line, said first block line comprising a plurality of blocks arranged in a horizontal direction in the image, wherein the first coding means is arranged to code the blocks included in the first block line by using arithmetic coding, and wherein the first coding means is arranged to update statistical information for arithmetic coding when coding the blocks included in the first block line; and second coding means for coding blocks included in a second block line of the slice in an order starting from a first block which is a left-most block of the second block line, said second block line comprising a plurality of blocks arranged in a horizontal direction in the image, wherein the second coding means is arranged to code the blocks included in the second block line by using arithmetic coding, and wherein when coding the first block of the second block line, the second coding means is arranged to use the statistical information updated when a predetermined block of the first block line is coded, wherein, the first coding means is arranged to code, for a quantization parameter of the first block in the order of coding the blocks included in the first block line, a difference value between the quantization parameter of the first block included in the first block line and a slice quantization parameter that is provided to the slice as an initial value, the second coding means is arranged to code, for a quantization parameter of the first block in the order of coding the blocks included in the second block line, a difference value between the quantization parameter of the first block included in the second block line and the slice quantization parameter that is used by the first coding means when coding the quantization parameter of the first block of the first block line, and quantization parameters of subsequent blocks of the first block of the first block line and quantization parameters of subsequent blocks of the first block of the second block line are coded by using the quantization parameter of a preceding block of the respective block line according to the order of coding.