A laser driving unit drives a semiconductor laser apparatus including a plurality of light sources, includes a light detecting part to detect light emissions from the light sources, a driving current generator to generate a driving current based on an input signal, an auxiliary driving current generator to generate an auxiliary driving current in an initial time period of an ON-time of the driving current, and an auxiliary current set part to set an auxiliary amount of the auxiliary driving current to be added to the driving current, for each of the light sources, based on a difference between the light emissions detected by the light detecting part and a target light emission of the light sources.