There is provided a highly accurate electrical
capacitance diaphragm
pressure sensor capable of reducing temperature drift that arises when a pressure-travel coefficient changes with temperature variations of a fluid whose pressure is sensed. A
sapphire diaphragm
pressure sensor, in which
sapphire diaphragms are arranged in opposing relation, comprises a
pressure sensing element (10, 30) having a pressure receiving part (10A, 30A) with a deposition
electrode formed on each of the opposing faces of
sapphire diaphragms which are provided in opposing relation to each other and a securing part with a
metal deposited on a part of each of the surfaces of the sapphire diaphragms, and further comprises a
metal base (11, 31) for securing the
pressure sensing element at the securing part of the
pressure sensing element, a conductive sealing agent (13, 33) for sealing a gap between the securing part on which a
metal is deposited and said metal base, and a
nickel protective layer (14, 34) for protecting at least said conductive sealing agent from a medium whose pressure is to be measured.