A semiconductor laser array device includes a semiconductor laser chip array including a plurality of laser chips each having a prescribed chip width mounted on a bar-shaped supporting substrate and arranged parallel to a length direction of the substrate and determined in position in the optical axis direction of the laser chip and in the length and height directions of the substrate; a monitor photodiode array including a plurality of monitor photodiodes arranged in an array with the same period as that of the laser chip array mounted on the substrate and arranged parallel with the length direction of the substrate and determined in position in the optical axis direction of the laser chips and in the length direction and the height direction of the substrate; a plurality of lenses mounted on the substrate arranged in the length direction of the substrate with the same period as that of the laser chip array, the lens positions being determined in the optical axis direction of the laser chip and in the length direction and the height direction of the substrate. A respective laser chip, monitor photodiode, and lens constitute an individual semiconductor laser device. The distance between the semiconductor laser chip and the monitor photodiode are determined with high precision.