To provide a pressure measurement device of a seal-structure wherein, being resistant against corrosion and low cost, no measurement fluid is leaked even at a low temperature.

A detector main body 1 comprising a seal diaphragm 2 and a process cover 3 are sealed up with an O ring 7a of a rubber group material wherein an U-shape or C-shape corrosion-resistant cover 8 of fluororesin group material is coated at least at such part as contacts to a to-be-measured fluid 4. With combination of sealing characteristics of a rubber group material which is elastic even at a low temperature and corrosion-resistance characteristics of the fluororesin group material, a low cost and corrosion resistant pressure measurement device is realized which can be used in a wide temperature range, from a low temperature to a high temperature.