A method for controlling a semiconductor device, the method comprising: controlling a gate voltage to be applied to a gate electrode of a junction field effect transistor including a source electrode, a drain electrode, and the gate electrode, the transistor having a first threshold voltage at which the transistor is turned on, and a second threshold voltage at which conductivity modulation occurs in the transistor so as to make the gate voltage equal to or higher than the second threshold voltage when it is desired to have a forward current to flow in a direction from the drain electrode toward the source electrode flows, so as to make the gate voltage have a point between the first threshold voltage and the second threshold voltage when it is desired to shut down the forward current, an absolute value of a rate of variation starts decreasing from the point, so as to subsequently maintain the gate voltage at a voltage between the second threshold voltage and the first threshold voltage for a predetermined time, and so as to subsequently make the gate voltage lower than the first threshold, when the forward current to be shut down, so as to make a difference between the gate voltage and a drain voltage equal to or higher than the second threshold voltage when it is desired to have a reverse current to flow in a direction from the source electrode toward the drain electrode, and so as to make the difference between the gate voltage and the drain voltage have a point between the first threshold voltage and the second threshold voltage from which an absolute value of a rate of variation starts decreasing and so as to subsequently keep the difference lower than the first threshold voltage when it is desired to shut down the reverse current. controlling a gate voltage to be applied to a gate electrode of a junction field effect transistor including a source electrode, a drain electrode, and the gate electrode, the transistor having a first threshold voltage at which the transistor is turned on, and a second threshold voltage at which conductivity modulation occurs in the transistor so as to make the gate voltage equal to or higher than the second threshold voltage when it is desired to have a forward current to flow in a direction from the drain electrode toward the source electrode flows, so as to make the gate voltage have a point between the first threshold voltage and the second threshold voltage when it is desired to shut down the forward current, an absolute value of a rate of variation starts decreasing from the point, so as to subsequently maintain the gate voltage at a voltage between the second threshold voltage and the first threshold voltage for a predetermined time, and so as to subsequently make the gate voltage lower than the first threshold, when the forward current to be shut down, so as to make a difference between the gate voltage and a drain voltage equal to or higher than the second threshold voltage when it is desired to have a reverse current to flow in a direction from the source electrode toward the drain electrode, and so as to make the difference between the gate voltage and the drain voltage have a point between the first threshold voltage and the second threshold voltage from which an absolute value of a rate of variation starts decreasing and so as to subsequently keep the difference lower than the first threshold voltage when it is desired to shut down the reverse current.