MEMS element and electro-acoustic conversion device

The invention discloses an MEMS element and an electro-acoustic conversion device. The MEMS element comprises a substrate, a first electrode, a second electrode, a third electrode and a fourth electrode, the vibrating diaphragm is connected with the substrate and covers the cavity, the vibrating diaphragm comprises a first diaphragm and a second diaphragm which are oppositely arranged, the first diaphragm is located on the side, away from the cavity, of the second diaphragm, and the first diaphragm comprises a first protrusion protruding out of the first diaphragm; the second diaphragm comprises a second protrusion protruding out of the second diaphragm, the second protrusion extends towards the side away from the first diaphragm, and the second protrusion and the first protrusion are oppositely arranged. The first diaphragm is provided with the first bulge, the second diaphragm is provided with the second bulge, and the first bulge and the second bulge are combined to form the corrugated vibrating diaphragm,