It is made possible to detect degradation in a circuit before an operation
fault will occur. A semiconductor integrated circuit includes: a circuit
to be tested; a plurality of logical circuits which have different
logical thresholds and which perform operation on an output of the
circuit to be tested, on the basis of the logical thresholds; and a
degradation notice signal generation circuit which generates a
degradation notice signal to give notice that the circuit to be tested
has degraded, when outputs of the logical circuits do not coincide with
each other.