A musical instrument playing actuator, includes an elastic diaphragm which has a through hole, wherein an annular projection portion is provided on the elastic diaphragm so as to project toward the diaphragm member, a diaphragm member which is arranged to oppose to the elastic diaphragm and is formed movably toward the elastic diaphragm, a wall structure body which forms an enclosed space together with the elastic diaphragm, the diaphragm member, and the projection portion when the diaphragm member is moved toward the elastic diaphragm to contact the projection portion, and an air inlet which communicates the enclosed space with an outside.