There is provided a semiconductor laser device which allows a stem body and a heat radiation block to be integrally fabricated even in small-size packages and which is low in price. Portions of leads 3A, 3B protruding on a reference surface side are placed on one side surface side of the heat radiation block 2 on which the semiconductor laser chip is mounted. Further, a cover 6 made of resin which is opened on the beam-output side of the semiconductor laser chip 4 is fixed to the heat radiation block 2 so as to surround the semiconductor laser chip 4 and the portions of the leads 3A, 3B protruding on the reference-surface side in conjunction with the heat radiation block 2.