1. A wireless communication device for performing equalization of wireless signals according to a characteristic through a transmission line, the wireless communication device comprising an equalizer which comprises: a correlation-information generation unit which generates a correlation matrix with a dimension of N×N representing autocorrelation of one or more first wireless signals, where N is an integer greater than one; a channel-vector generation unit which generates a channel vector with a dimension of N on the basis of the first wireless signals; an extended-correlation-matrix generation unit which generates an extended correlation matrix with a dimension of 2N×2N, where the extended correlation matrix is a circulant matrix containing the correlation matrix with a dimension of N×N; a channel-vector extension unit which generates an extended channel vector with a dimension of 2N by extending said channel vector; a weight-coefficient calculation unit which calculates an extended weight coefficient vector with a dimension of 2N as a solution of an equation expressed by said extended correlation matrix and said extended channel vector, wherein the weight-coefficient calculation unit is configured to solve the equation by repeating a first frequency-domain calculation for the extended channel vector and a second frequency-domain calculation for the extended weight coefficient vector, while the first and second frequency-domain calculations use a part of each other's results so as to increase precision of the extended weight coefficient vector; and a synthesis unit which generates an equalized signal by using N elements out of the calculated extended weight coefficient vector and one or more second wireless signals received through one or more receiver antennas.