The MEMS sensor according to the present invention includes a diaphragm. In the diaphragm, an angle formed by two straight lines connecting supporting portions and the center of a main portion with one another respectively is set to satisfy the relation of the following formula (1): (A2/A1)/(B2/B1)≧1  (1) A2: maximum vibrational amplitude of the diaphragm in a case of working a physical quantity of a prescribed value on the diaphragm A1: maximum vibrational amplitude of the diaphragm in a case of working the physical quantity on the diaphragm in an omitting structure obtained by omitting one of the supporting portions from the diaphragm B2: maximum stress caused in the diaphragm in the case of working the physical quantity on the diaphragm B1: maximum stress caused in the diaphragm in the case of working the physical quantity on the diaphragm in the omitting structure.