In a rotation detection apparatus, a rotation-angle detector detects a
rotation angle of a rotating body based on an output signal generated by
a resolver. An exciting-signal generation circuit supplies an exciting
signal for exiting the resolver to generate the output signal. An
abnormality detection circuit detects an abnormality of an
exciting-signal output terminal for outputting the exciting signal or an
abnormality of an exciting-signal line for transmitting the exciting
signal. A power-supply stopping circuit stops a power supply to the
exciting-signal generation circuit when the abnormality detection circuit
detects an abnormality of the exciting-signal output terminal or detects
an abnormality of the exciting-signal line.