An object of the present invention is to provide a loudspeaker device which has a high moisture resistance and can further widens an audio range of low-frequency range sounds. To achieve the above object, a closed box loudspeaker device of the present invention includes a loudspeaker unit which is attached to an opening in a box and activated carbon fiber which is provided in the box to adsorb gas. The activated carbon fiber has plural pores, which are exposed on a surface of the activated carbon fiber and have a diameter of 2.0 nm or less, and a volume of the pores having the diameter of 2.0 nm or less occupies 60% or more of a volume of the entire pores, so that the loudspeaker device which simultaneously achieves both an enhancement of the moisture resistance and the widening of the audio range of the low-frequency range sounds can be provided.