A micro-electro-mechanical system (MEMS) microphone is provided. The MEMS microphone includes a substrate, a diaphragm, a backplate and a first protrusion. The substrate has an opening portion. The diaphragm is disposed on one side of the substrate and extends across the opening portion of the substrate. The backplate includes a plurality of acoustic holes. The backplate is disposed on one side of the diaphragm. An air gap is formed between the backplate and the diaphragm. The first protrusion extends from the backplate towards the air gap.