A semiconductor laser light source device and light source unit according to the present invention include a first plate-like member made of metal, to which a semiconductor laser array is joined along the end portion, a second plate-like member made of metal, in which an inlet opening portion, which introduces cooling fluid, and a cooling fluid draining channel, and a third plate-like member made of metal, which is formed along the area corresponding to the end portion and to which at least one cooling channel is provided through which cooling fluid flows in the longitudinal direction of the semiconductor laser array by communicating the cooling fluid introducing channel and the cooling fluid draining channel. Thus, the sectional area of the channel can be larger than that in the construction of the related art and the processing cost is reduced by comparison with the construction of the related art. The problems of blocking path with an extraneous matter and of high-pressure loss due to the path are overcome. Since the channel is provided along the longitudinal direction of the semiconductor laser array, the semiconductor laser array can be cooled efficiently.