A method of transmitting a feedback frame in a wireless LAN, WLAN, system, the method comprising: generating, by a first station, STA, the feedback frame based on a multi input multi output, MIMO, beamforming procedure; and transmitting, by the first STA, the feedback frame to a second STA, and the method characterized in that: when the feedback frame is transmitted through an aggregated channel in which a first channel and a second channel are aggregated and have different bands, the feedback frame comprises a first beamforming feedback matrix transmitted on the first channel and a second beamforming feedback matrix transmitted on the second channel, and when the feedback frame is not transmitted through the aggregated channel, the feedback frame comprises a third beamforming matrix, wherein the number of columns of the third beamforming feedback matrix is set to Nc, the number of rows of the third beamforming feedback matrix is set to Nr, and Nc and Nr are determined based on a total number of spatial streams supported by the first STA, wherein the number of columns of the first beamforming feedback matrix is set to Nc/2, and the number of rows of the first beamforming feedback matrix is set to Nr/2, wherein the number of columns of the second beamforming feedback matrix is set to Nc/2, and the number of rows of the second beamforming feedback matrix is set to Nr/2, wherein a number of feedback bits of the first and second beamforming feedback matrixes is determined based on a feedback type, and wherein Nc and Nr are even numbers. generating, by a first station, STA, the feedback frame based on a multi input multi output, MIMO, beamforming procedure; and transmitting, by the first STA, the feedback frame to a second STA, and the method characterized in that: when the feedback frame is transmitted through an aggregated channel in which a first channel and a second channel are aggregated and have different bands, the feedback frame comprises a first beamforming feedback matrix transmitted on the first channel and a second beamforming feedback matrix transmitted on the second channel, and when the feedback frame is not transmitted through the aggregated channel, the feedback frame comprises a third beamforming matrix, wherein the number of columns of the third beamforming feedback matrix is set to Nc, the number of rows of the third beamforming feedback matrix is set to Nr, and Nc and Nr are determined based on a total number of spatial streams supported by the first STA, wherein the number of columns of the first beamforming feedback matrix is set to Nc/2, and the number of rows of the first beamforming feedback matrix is set to Nr/2, wherein the number of columns of the second beamforming feedback matrix is set to Nc/2, and the number of rows of the second beamforming feedback matrix is set to Nr/2, wherein a number of feedback bits of the first and second beamforming feedback matrixes is determined based on a feedback type, and wherein Nc and Nr are even numbers. when the feedback frame is transmitted through an aggregated channel in which a first channel and a second channel are aggregated and have different bands, the feedback frame comprises a first beamforming feedback matrix transmitted on the first channel and a second beamforming feedback matrix transmitted on the second channel, and when the feedback frame is not transmitted through the aggregated channel, the feedback frame comprises a third beamforming matrix, wherein the number of columns of the third beamforming feedback matrix is set to Nc, the number of rows of the third beamforming feedback matrix is set to Nr, and Nc and Nr are determined based on a total number of spatial streams supported by the first STA, wherein the number of columns of the first beamforming feedback matrix is set to Nc/2, and the number of rows of the first beamforming feedback matrix is set to Nr/2, wherein the number of columns of the second beamforming feedback matrix is set to Nc/2, and the number of rows of the second beamforming feedback matrix is set to Nr/2, wherein a number of feedback bits of the first and second beamforming feedback matrixes is determined based on a feedback type, and wherein Nc and Nr are even numbers.