A short-circuit fault detection device detects a short-circuit fault in a step-up and step-down DC-DC converter that takes generated power of a solar cell as an input and outputs a predetermined voltage to a power storage. The DC-DC converter includes a step-up upper arm, a step-up lower arm, a step-down upper arm, and a step-down lower arm. The short-circuit fault detection device includes a voltage detection unit detecting a voltage output to the DC-DC converter from the solar cell, a current detection unit detecting a current output to the power storage from the DC-DC converter, and a controller controlling switching elements constituting the DC-DC converter to determine whether each arm of the DC-DC converter has a short-circuit fault based on a detected voltage value that is a detected value of the voltage detection unit, and a detected current value that is a detected value of the current detection unit.