PURPOSE: To obtain an automobile audio speaker system which has satisfactory frequency response and does not occupy a large space by a method wherein low sound speakers are arranged in the back part of a trunk so as not to interfere a rear deck.

CONSTITUTION: Low sound speakers are arranged in an automobile trunk 1 so as to be separated from an automobile cabin by a dividing part 11 and a rear deck 3. The dividing part 11 is a fixed component or a movable component such as a folding rear seat. The speakers are installed in speaker enclosures 9 adjacent to the dividing part 11. As the speakers do not need holes penetrating the rear deck 3, noise leaking into the cabin from a road side is suppressed. The rear deck 3 has influence upon low frequency sound and the trunk 1 functions as a natural low-pass filter as a whole. Further, the sizes of the speaker enclosures 9 arranged in the corners 7 of the trunk 1 can be reduced, so that the sizes of the speakers can be reduced.