To prevent a reduction in strength based on the filler liquid of a glass structure within a pressure sensor vessel by using a filler liquid defoamed after dehydration as the filler liquid.

A filler liquid 201 is sealed in a space formed by a pressure vessel 8, a sensor chip 1 and a glass support base 5. A filler liquid 202 is sealed on the side of a pressure inlet chamber 6 and a communicating hole 7. As the filler liquids 201, 202, silicon oil defoamed under vacuum after dehydration is used. When pressure PH is added to the filler liquid 201, and pressure PL to the filler liquid 202, a diaphragm 3 is displaced by the pressure of pressure PH-pressure PL. This displacement is electrically detected by a semiconductor pressure detecting element 4, whereby an electric signal output corresponding to pressure PH-pressure PL can be provided. By sealing such dehydrated filler liquids 201, 202, moisture can be prevented from being adsorbed to the glass structure surface, so that the reduction in strength can be prevented.