PURPOSE: To obtain a pressure transmitter not damaging a product even when a sealing soln. leaks by the damage of a diaphragm and excellent in pollution control and safety by filling the space filled with the sealing soln. with an insulating material and employing an extremely fine pipe as a capillary tube.

CONSTITUTION: A pressure transmission medium 4 is sealed in a main body 1 and the pressure detected by a seal diaphragm 6 is transmitted to a pressure converting element 2 through the medium 4. As the sealing soln. (pressure transmission medium) 4, silicon oil or fluorine oil high in the values of a compression ratio and the coefficient of thermal expansion as compared with mercury is used. The insulating material 5 of the main body 1 fills the internal space of the main body to develop the function reducing the amt. of the medium 4 to be sealed. The main body 1 and a liquid contact part 7 are connected by an extremely fine pipe or capillary tube 8 composed of a double pipe having fixing metal fittings 9 connected to both ends thereof. The fixing metal fitting 9 is connected to the main body 1 and the liquid contact part 7 by welding and connectors 10 are bonded to the main body 1 and the liquid contact part 7 by welding. By this constitution, the damage of a product accompanied by the damage of the seal diaphragm 6 is prevented and pressure can be stably detected.