To optionally set a set value of excessive pressure that a diaphragm of a differential pressure/pressure transmitter reacts to.

A differential pressure/pressure transmitter including a main body 1 having a high pressure-side pressure reception part and a low pressure-side pressure reception part, a pressure sensor 2 installed in the main body 1, a high pressure-side center diaphragm 19 provided to the high pressure-side pressure reception part, high pressure-side fixing metal fittings 7 which have a convex surface, a low pressure-side center diaphragm 20 provided to the low pressure-side pressure reception part, and low pressure-side fixing metal fittings 8 which have a convex surface is configured such that while the convex surface of the high pressure-side fixing metal fittings 7 is pressed against the high pressure-side center diaphragm 19 and the pressing quantity can be varied by a threadable engagement mechanism, the convex surface of the low pressure-side fixing metal fittings 8 is pressed against the low pressure-side center diaphragm 20 and the pressing quantity can be varied by the threadable engagement mechanism.