According to one embodiment, a protection circuit is a protection circuit for protecting an output driver element from overheat, and includes a measurer configured to measure, as a measurement value, a value proportional to a supply power amount to the output driver element, an estimator configured to estimate a temperature rise amount of the output driver element corresponding to the supply power amount, on a basis of the measurement value, a detector configured to detect an ambient temperature of the output driver element, and a determiner configured to determine whether a temperature obtained by adding the temperature rise amount estimated to the ambient temperature exceeds a predetermined threshold temperature, and to output a cutoff instruction signal for the output driver element.