A speaker unit is arranged in a casing of an electronic apparatus. The speaker unit includes a cabinet, a speaker arranged in the cabinet and exposed to the outside of the cabinet, and a port which is defined in the cabinet to open the outside of the cabinet and through which a sound emitted from the backside of the speaker into the cabinet is radiated outward from the cabinet. The speaker is exposed to the outside of the casing through an opening defined in an outside wall of the casing. The port of the speaker unit opens into the casing.