1. An inverse quantization method for obtaining inverse-quantized orthogonal transform coefficients using an inverse quantization unit, by inverse-quantizing quantized orthogonal transform coefficients, said method comprising: obtaining, using the inverse quantization unit, a weighting matrix; obtaining, using the inverse quantization unit, a quantization parameter; calculating, using the inverse quantization unit a level scale value by multiplying a value, which is calculated from a component in i-th row and j-th column in the weighting matrix, and a normalization value, which is corresponding to the position of the component in i-th row and j-th column in the weighting matrix and a remainder of the quantization parameter divided by an integer equal to or greater than 2; multiplying, using the inverse quantization unit, a quantized orthogonal transform coefficient and the level scale value; and shifting, using the inverse quantization unit, a product resulted from a multiplication by the number of bits in accordance with the quantization parameter so as to obtain an inverse-quantized orthogonal transform coefficient.