A drive control apparatus for a semiconductor device having a diode and a transistor includes: a current detection device of a current flowing through the diode; and a control device, which applies a gate drive voltage to the semiconductor device when an on-instruction signal is input. The control device compares the current detection signal with a current threshold value during a first period, in which the on-instruction signal is input, after a second period has elapsed from gate drive voltage application time, or gate drive voltage shut-off time. A transient variation is generated on the current detection signal in the second period. The control device shuts off the gate drive voltage when the current detection signal is equal to or larger than the current threshold value. The control device applies the gate drive voltage when the current detection signal is smaller than the current threshold value.