In a semiconductor laser module incorporating a driving circuit therein, which contains a semiconductor laser mounted on an electronic cooling element and a semiconductor laser driving IC within the same package, is provided an electrode lead on a stem for mounting a semiconductor laser, for connecting the semiconductor laser with a board carrying a driving IC and the dimensions of the electrode lead are defined so as to reduce the stray capacitance and the parasitic inductance and to optimize the thermal resistance. A gap of a value not to introduce an increase of an unnecessary inductance between the semiconductor laser mounting portion and the driver IC mounting board is provided to spatially divide the semiconductor laser mounting portion and the driver IC mounting board. Thereby, the inflow of the heat generated in a driver IC into a semiconductor laser mounted on an electronic cooling element can be suppressed without degrading the high speed modulation characteristics in the giga-bits band.