A power conversion system includes: a switching element; an output circuit that outputs a transmission signal for transmitting information on a physical quantity that indicates a state of the switching element and for transmitting information on abnormality of the switching element; an isolating element that transmits the transmission signal in an electrically isolated state; a filter that deletes the information on the physical quantity from a signal transmitted through the isolating element; a control circuit to which the signal transmitted through the isolating element but not through the filter is input; and a shutdown circuit that shuts down power supply to the switching element on the basis of the signal through the filter.