A light-source device of a multi-beam scanning apparatus including a plurality of semiconductor lasers, collimator lenses provided for the semiconductor lasers and a holder member integrally holding the semiconductor lasers and the collimator lenses. The semiconductor lasers are pressed into the holder member, and the collimator lenses are bonded to the holder member with a part of each edge portion of the collimator lenses adjusted in position relative to said holder member. Positions of press-in portions of the holder member for the semiconductor lasers are relatively deviated and formed in such a manner that adhesive layers for bonding the holder member and the collimator lenses have a same thickness.