An equalizer, for a wireless communication device, for performing equalization of wireless signals, the equalizer comprising: a correlation-information generation unit configured to generate a correlation matrix with a dimension of M × M representing autocorrelation in one or more wireless training signals received through one or more receiver antennas, where M is an integer greater than one; a channel-vector generation unit configured to generate a channel vector with a dimension of M on the basis of said one or more wireless training signals; an extended-correlation-matrix generation unit configured to generate an extended correlation matrix with a dimension of 2M × 2M, where the extended correlation matrix is a circulant matrix containing the correlation matrix with a dimension of M × M; a channel-vector extension unit configured to generate an extended channel vector with a dimension of 2M by extending said channel vector so that the extended channel vector contains the channel vector and one or more zeros; a weight-coefficient calculation unit configured to calculate an extended weight coefficient vector with a dimension of 2M as a solution of an equation expressed by said extended correlation matrix and said extended channel vector, where 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 result, until the solution converges; and a synthesis unit configured to generate an equalized signal by using M elements out of the calculated extended weight coefficient vector and one or more wireless signals received through said one or more receiver antennas. a correlation-information generation unit configured to generate a correlation matrix with a dimension of M × M representing autocorrelation in one or more wireless training signals received through one or more receiver antennas, where M is an integer greater than one; a channel-vector generation unit configured to generate a channel vector with a dimension of M on the basis of said one or more wireless training signals; an extended-correlation-matrix generation unit configured to generate an extended correlation matrix with a dimension of 2M × 2M, where the extended correlation matrix is a circulant matrix containing the correlation matrix with a dimension of M × M; a channel-vector extension unit configured to generate an extended channel vector with a dimension of 2M by extending said channel vector so that the extended channel vector contains the channel vector and one or more zeros; a weight-coefficient calculation unit configured to calculate an extended weight coefficient vector with a dimension of 2M as a solution of an equation expressed by said extended correlation matrix and said extended channel vector, where 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 result, until the solution converges; and a synthesis unit configured to generate an equalized signal by using M elements out of the calculated extended weight coefficient vector and one or more wireless signals received through said one or more receiver antennas.