The sensor comprises a needle member having a hollow portion and a through hole, a long sensing member positioned in the hollow portion and extending along the extending direction to the peripheral wall of the needle member, which protrudes inward in the radial direction of the needle member to regulate the radial movement of the detecting member It is characterized in that projections are provided.センサは、中空部を区画し、貫通孔を有する針部材と、前記中空部に位置し、前記針部材の周壁には、延在方向に沿って延在する長尺状の検出部材と、を備え、前記周壁には、前記針部材の径方向の内側に突出し、前記検出部材の前記径方向への移動を規制する突起部が設けられている、ことを特徴とする。
