There is provided an electric-power conversion apparatus that can protect semiconductor switching devices in accordance with the ambient temperature. The electric-power conversion apparatus includes a comparator that generates an output based on a comparison between the output of a sensor and a threshold value, a reference voltage circuit that produces the threshold value, and a control circuit that is configured in such a way as to be able to stop operation of a main circuit, based on the output of the comparator; the reference voltage circuit is configured in such a way as to change the threshold value in accordance with an ambient temperature under which semiconductor switching devices are laid.