A power converter having a semiconductor switching element, comprising: the semiconductor switching element; a driving circuit of the semiconductor switching element; a power control circuit; an applied voltage suppression circuit configured to detect an applied voltage (Vce) to the semiconductor switching element, and to feed back a difference signal based on a difference between the applied voltage (Vce) and a predetermined voltage to a control terminal of the semiconductor switching element when the applied voltage (Vce) is the predetermined voltage or more, thereby suppressing the applied voltage (Vce) to the predetermined voltage or in the vicinity thereof, said applied voltage (Vce) being applied across the terminals of the semiconductor switching element other than the control terminal; characterized by: a first substrate on which the semiconductor switching element, the driving circuit, the power control circuit are mounted; a second substrate divided from and electrically connected to the first substrate, wherein the applied voltage suppression circuit is disposed on the second substrate; wherein the second substrate is a separate unit and is inspectable independently and separate from the first substrate; connection means provided on the second substrate; and a DC power supply electrically connected to the driving circuit via said connection means; wherein the driving circuit is configured to not output an ON signal to the control terminal of the semiconductor switching element if the connection means is absent and output an ON signal to the control terminal of the semiconductor switching element if the connection means is present, wherein the ON signal is configured to cause the semiconductor switching element to be turned on. the semiconductor switching element; a driving circuit of the semiconductor switching element; a power control circuit; an applied voltage suppression circuit configured to detect an applied voltage (Vce) to the semiconductor switching element, and to feed back a difference signal based on a difference between the applied voltage (Vce) and a predetermined voltage to a control terminal of the semiconductor switching element when the applied voltage (Vce) is the predetermined voltage or more, thereby suppressing the applied voltage (Vce) to the predetermined voltage or in the vicinity thereof, said applied voltage (Vce) being applied across the terminals of the semiconductor switching element other than the control terminal; characterized by: a first substrate on which the semiconductor switching element, the driving circuit, the power control circuit are mounted; a second substrate divided from and electrically connected to the first substrate, wherein the applied voltage suppression circuit is disposed on the second substrate; wherein the second substrate is a separate unit and is inspectable independently and separate from the first substrate; connection means provided on the second substrate; and a DC power supply electrically connected to the driving circuit via said connection means; wherein the driving circuit is configured to not output an ON signal to the control terminal of the semiconductor switching element if the connection means is absent and output an ON signal to the control terminal of the semiconductor switching element if the connection means is present, wherein the ON signal is configured to cause the semiconductor switching element to be turned on. a first substrate on which the semiconductor switching element, the driving circuit, the power control circuit are mounted; a second substrate divided from and electrically connected to the first substrate, wherein the applied voltage suppression circuit is disposed on the second substrate; wherein the second substrate is a separate unit and is inspectable independently and separate from the first substrate; connection means provided on the second substrate; and a DC power supply electrically connected to the driving circuit via said connection means; wherein the driving circuit is configured to not output an ON signal to the control terminal of the semiconductor switching element if the connection means is absent and output an ON signal to the control terminal of the semiconductor switching element if the connection means is present, wherein the ON signal is configured to cause the semiconductor switching element to be turned on.