A signal processing circuit respectively transforms complex covariance matrices, which are consecutively inputted at a predetermined period, into upper triangular matrices. The signal processing circuit includes: a storage unit that stores at least N-number of complex covariance matrices; a reading unit that reads matrix elements of the stored complex covariance matrices; a CORDIC calculation circuit that implements a CORDIC algorithm by a pipelined circuit system; and a QR decomposition unit that controls the reading unit and the CORDIC calculation circuit unit to calculate an upper triangular matrix by iteratively using the CORDIC calculation circuit unit on a single complex covariance matrix and that calculates in parallel a transformation of N-number of complex covariance matrices into upper triangular matrices in an interleaved format.