Abstract: A microphone device includes a carrier board, a micro electro-mechanical system unit, an integrated circuit and an upper cover. The micro electro-mechanical system unit includes a substrate, a cap and a capacitive microphone. The cap is installed on the substrate, and is composed of electrically conductive material. The capacitive microphone is positioned between the cap and the carrier board, wherein the capacitive microphone and the cap form a resonant cavity. The integrated circuit is installed on the carrier board, and arranged to control the capacitive microphone. The upper cover is connected to the carrier board, wherein the micro-electro mechanical system unit and the integrated circuit are both positioned inside a space formed by the carrier board and the upper cover.