An on-board switching device includes: a switching circuit; a first conduction path through which a current flows in a series connection state and no current flows in a parallel connection state; a second conduction path through which a current flows in the parallel connection state and no current flows in the series connection state; a third conduction path that forms a path between a negative electrode of a first battery and a positive electrode of a second battery in the series connection state and forms a path between both positive electrodes or between both negative electrodes of the first battery and the second battery in the parallel connection state; and a current detection unit that detects a current flowing through the third conduction path.