PURPOSE: To obtain a differential pressure and pressure detector which is not deteriorated due to ambient temperature, by selecting a thermal expansion factor of an annular body forming a pressure detector, and that of a displacement electric signal converting part so that they become equal to each other substantially.

CONSTITUTION: When a thermal expansion factor of an annular body 11 to which diaphragms 12, 13, etc. have been welded and fixed, and a mean thermal expansion factor of a displacement electric signal converting part 16 formed by cuplike conversion holding members 17, 18, insulating members 21, 22, a plate spring 19 displaced by differential pressure, capacity variation measuring electrodes 23, 24 responding to displacement, etc. are selected so as to be equal to each other substantially, a differential pressure and pressure detector constituted of them is not affected by a variation of an ambient temperature, and its performance is not deteriorated by ambient temperatures.