a quantizing device for more efficient quantization realized by lessening the computational complexity of quantization of a balance weighting factor . the device includes a power / correlation calculating unit , an intermediate value calculating unit , a codebook , a searching unit , and a decoding unit . the power / correlation calculating unit determines the value of the correlation between an l signal and an m signal and the value of the correlation between an r signal and the m signal and calculates the power of the m signal . the intermediate value calculating unit determines two intermediate values by using the power of the m signal and the values of the correlations . the codebook holds scalar values . the searching unit selects a coefficient for balance adjustment of the amplitude of the m signal with respect to the l signal from among the scalar values according to the two intermediate values . the decoding unit determines the coefficient for balance adjustment of the m signal with respect to the r signal by using the selected coefficient for balance adjustment of the m signal with respect to the l signal on the basis of the quantitative relation between the amplitudes of the signals of when the m signal is generated by down - mixing the l and r signals .