Abstract: A test object includes a first semiconductor element, a first main electrode electrically connected to a positive electrode of the first semiconductor element, a second main electrode electrically connected to a negative electrode of the first semiconductor element, and a first capacitor connected between the first main electrode and the second main electrode. A semiconductor testing device comprises a DC power supply connected between a first probe and a second probe, and a controller. When the first probe is connected to the first main electrode and the second probe is connected to the second main electrode, the controller charges the first capacitor with a DC voltage supplied from a DC power supply, and inputs, to a control electrode of the first semiconductor element, a control signal for turning on the first semiconductor element, after charging the first capacitor.