A vector quantizer which improves the accuracy of vector quantization in switching over a vector quantization codebook on a first stage depending on the type of feature having the correlation with a quantization target vector. In the vector quantizer, a classifier generates classification information representing a type of narrowband LSP vector having the correlation with wideband LSP (Line Spectral Pairs) of the plural types. A first codebook selects one sub-codebook corresponding to the classification information as a codebook used for the quantization of the first stage from plural sub-codebooks corresponding to each of the types of narrowband LSP vectors. A multiplier multiplies the quantization residual vector of the first stage inputted from an adder by a scaling factor corresponding to the classification information of plural scaling factors stored in a scaling factor determiner and outputs it to an adder as the quantization target of a second stage.