Abstract: A communication module that may be smaller in size but capable of providing a high-rate communication with an excellent high frequency characteristic includes a semiconductor laser (LD) (10); a flexible printed circuit board (FPC) (11) on which the LD (10) is mounted and to which the LD (10) is electrically connected; a stem (12) through which the FPC (11) is inserted and to which the FPC (11) is then fixed; and a cap (13) so disposed as to cover the LD (10). The FPC (11) is used, instead of lead pins, to supply a power to the LD (10), derive signals therefrom and so on, whereby the high frequency characteristic can be improved. In addition, employment of a package structure comprising the stem (12) and cap (13) realizes the smaller size.