A semiconductor laser driving device that drives a semiconductor laser with a driving current output from a driving current output terminal is disclosed. The semiconductor laser driving device includes a driving current monitoring terminal configured to output a driving current monitoring current having a value of 1/α of the driving current; a current-voltage conversion resistor connected to the driving current monitoring terminal and configured to convert the driving current monitoring current having the value of 1/α of the driving current into a corresponding driving current monitoring voltage; and a detector configured to generate a reference voltage and detect whether the corresponding driving current monitoring voltage has reached the reference voltage.