A pressure sensor micromachined by using microelectronics technologies includes a cavity hermetically sealed on one side by a silicon substrate and on the other side by a diaphragm that is configured to be formed under the effect of the pressure outside the cavity. The sensor includes at least one resistance strain gage fastened to the diaphragm and has resistance that varies as a function of the deformation of the diaphragm. The diaphragm is fastened to the resistance strain gages. The gages are located inside the sealed cavity. The diaphragm has an insulting layer deposited on a sacrificial layer and may cover integrated measurement circuits in the silicon substrate.