The system identifying device preferably includes adaptive and dependent filters which receive a signal supplied through a first input terminal, a dependent filter factor updating unit for updating the filter factor of the dependent filter according to the filter factor of the adaptive filter, a first subtracter for subtracting the output signal outputted from the adaptive filter from the signal supplied through a second input terminal, a first output error mean computing section for computing a first output error mean from the output signal outputted from the first subtracter, a second subtracter for subtracting the output signal outputted from the dependent filter from the signal supplied through the second input terminal, a second output error mean computing section for computing a second output error mean from the output signal outputted from the second subtracter, and a compactor for comparing the first and second output error means.
