A pressure sensor comprising: a housing extending in a predetermined axial direction (S) and including a tip tubular portion exposed to a pressured medium; an output measurement unit including a piezoelectric member accommodated in the housing ; and a pressure transmission member configured to close an accommodating space (A) of the output measurement unit in the housing and transmit a pressure of the pressured medium applied in the axial direction (S) to the output measurement unit , wherein the pressure transmission member is a bottomed diaphragm , and the pressure transmission member includes an inner tubular portion fixed to a tip portion of the tip tubular portion and extending in the axial direction (S) toward the output measurement unit inside the tip tubular portion , and a pressure receiving bottom portion formed integrally with the inner tubular portion and abutting the output measurement unit , the pressure sensor being characterized in that the tip tubular portion and the inner tubular portion are formed to have substantially the same thermal deformation amount in the axial direction (S), and that the housing includes a seal portion configured to seal the pressured medium around the tip tubular portion and at a predetermined position retracted from an end surface of the tip tubular portion , and a length (D1) of the inner tubular portion of the diaphragm in the axial direction (S) is substantially the same as a length (D2) in the axial direction (S) from the end surface of the tip tubular portion to the seal portion such that a contact position between the pressure receiving bottom portion and the output measurement unit is maintained. a housing extending in a predetermined axial direction (S) and including a tip tubular portion exposed to a pressured medium; an output measurement unit including a piezoelectric member accommodated in the housing ; and a pressure transmission member configured to close an accommodating space (A) of the output measurement unit in the housing and transmit a pressure of the pressured medium applied in the axial direction (S) to the output measurement unit , wherein the pressure transmission member is a bottomed diaphragm , and the pressure transmission member includes an inner tubular portion fixed to a tip portion of the tip tubular portion and extending in the axial direction (S) toward the output measurement unit inside the tip tubular portion , and a pressure receiving bottom portion formed integrally with the inner tubular portion and abutting the output measurement unit , the pressure sensor being characterized in that the tip tubular portion and the inner tubular portion are formed to have substantially the same thermal deformation amount in the axial direction (S), and that the housing includes a seal portion configured to seal the pressured medium around the tip tubular portion and at a predetermined position retracted from an end surface of the tip tubular portion , and a length (D1) of the inner tubular portion of the diaphragm in the axial direction (S) is substantially the same as a length (D2) in the axial direction (S) from the end surface of the tip tubular portion to the seal portion such that a contact position between the pressure receiving bottom portion and the output measurement unit is maintained. <EOS>