To enable a factor estimating device for adaptive filter of multichannel system which simulates the characteristics of a plurality of signal transmission systems to estimate the impulse response of each signal transmitting system with high accuracy even when a correlation exists between reference signals in a multichannel system.

A correlation eliminating circuit that removes the intercorrelated component between a reference signal impressed upon a signal transmitting system which becomes an object to be processed and another reference signal. The device is constituted to generate a residual reference signal vector from the output of the correlation removing circuit and a vector component from the reference signal impressed upon the signal transmitting system to be processed, to calculate the correlation between the residual reference signal vector and reference signal vector by inputting the vectors and the correlation between the residue of the outputs of the signal transmitting system to be processed and the adaptive filter and residual reference signal vector, to normalize the output obtained through the calculation with the output about the correlation between the vectors, and to update the preceding coefficient with the normalized output.