PURPOSE: To provide a liquid pressure measuring sensor with its minimized pressure error, high reliability, high rigidity, high durability, and excellent air tightness.

CONSTITUTION: A liquid pressure measuring sensor comprises a diaphragm capsule insertion ring 7 fitted and provided with its air tightness maintained in an external body 3, a ceramic diaphragm capsule 11 provided in this diaphragm capsule insertion ring 7 and fixed by means of a diaphragm capsule fixing ring 13, a strain gauge element circuit provided for a pressure receiving port diaphragm capsule 11A provided on one side surface of the ceramic diaphragm capsule 11, and a sealing chamber 31 in which liquid is not easily mixed with liquid to be measured is provided between one side surface of the ceramic diaphragm capsule 11 and the diaphragm capsule insertion ring 7 for communicating one end of a thin tube 33 in which liquid is sealed, communicating the other end of the thin tube 33 with the liquid targeted for measurement, and communicating the other side surface of the pressure receiving part ceramic diaphragm 11A with the atmosphere.