A speaker module for a mobile device is provided. The speaker module changes a shape of an opening surface of a duct to which a protection member for preventing a foreign substance from entering is attached. The speaker module includes a speaker for outputting a sound signal, a body in which the speaker is mounted, a duct connected to the body for forming a radiation path of a sound signal output from the speaker, and a protection member attached to an opening surface of the duct for preventing a foreign substance from entering the speaker module, wherein the opening surface has an area larger than that of a cross-sectional opening surface formed vertically with respect to a length direction of the duct.