An image decoding apparatus for decoding a bit stream includes a receiving unit that receives the bit stream and a weight parameter that is added to a luma quantization parameter. Further, the image decoding apparatus includes a decoding unit that decodes the bit stream and generates a chroma component of quantized coefficients. The image decoding apparatus also includes a setting unit that sets a chroma quantization parameter calculated on the basis of the luma quantization parameter weighted by an addition operation that adds the weight parameter. Additionally, the image decoding apparatus includes a dequantization unit that performs dequantization on the chroma component of quantized coefficients using the chroma quantization parameter. In addition, the image decoding apparatus includes a transform unit that performs an inverse orthogonal transform.