A pressure sensor comprising: a sensor unit including a housing , a sensor chip for detecting a pressure and sending a detection output signal, a chip mounting member supporting the sensor chip , a diaphragm supported by a lower end surface of the housing for partitioning a liquid sealing chamber , in which the sensor chip is placed, from a pressure chamber facing the liquid sealing chamber , and a group of input-output terminals supported by a hermetic glass and electrically connected to the sensor chip ; the housing , the hermetic glass , the chip mounting member , and the diaphragm forming the liquid sealing chamber ; and an electric field blocking member placed between one end surface of the sensor chip in the liquid sealing chamber and the diaphragm , and for blocking an electric field acting on a signal processing electronic circuit unit of the sensor chip , wherein the electric potential of the electric field blocking member is set to the same electric potential as that of the electronic circuit of the sensor chip , characterized in that the electric field blocking member is strip-shaped and comprises a trench-shaped portion facing the one end surface of the sensor chip and passing immediately above a central part of the sensor chip with a predetermined clearance, and first and second fixing portions continued to both end portions of the trench-shaped portion , and an oil filling pipe is press-fitted into a hole in the first fixing portion , the group of input-output terminals projecting from the end surface of the hermetic glass are inserted into holes and a notch portion of the second fixing portion , the electric field blocking member is electrically connected to one of the group of input-output terminals , and the first and second fixing portions are supported on an end surface of the hermetic glass . a sensor unit including a housing , a sensor chip for detecting a pressure and sending a detection output signal, a chip mounting member supporting the sensor chip , a diaphragm supported by a lower end surface of the housing for partitioning a liquid sealing chamber , in which the sensor chip is placed, from a pressure chamber facing the liquid sealing chamber , and a group of input-output terminals supported by a hermetic glass and electrically connected to the sensor chip ; the housing , the hermetic glass , the chip mounting member , and the diaphragm forming the liquid sealing chamber ; and an electric field blocking member placed between one end surface of the sensor chip in the liquid sealing chamber and the diaphragm , and for blocking an electric field acting on a signal processing electronic circuit unit of the sensor chip , wherein the electric potential of the electric field blocking member is set to the same electric potential as that of the electronic circuit of the sensor chip , characterized in that the electric field blocking member is strip-shaped and comprises a trench-shaped portion facing the one end surface of the sensor chip and passing immediately above a central part of the sensor chip with a predetermined clearance, and first and second fixing portions continued to both end portions of the trench-shaped portion , and an oil filling pipe is press-fitted into a hole in the first fixing portion , the group of input-output terminals projecting from the end surface of the hermetic glass are inserted into holes and a notch portion of the second fixing portion , the electric field blocking member is electrically connected to one of the group of input-output terminals , and the first and second fixing portions are supported on an end surface of the hermetic glass . <EOS>