A sensor comprising: a detection element in the form of an axially extending plate, having a front end side to face an object to be measured and formed with an electrode terminal section (30, 31, 32, 34, 36) at a rear end side; a separator made of an insulating material and having an element insertion hole accommodating the rear end side of the detection element; and a metallic terminal member interposed between the detection element and an inner surface of the element insertion hole of the separator; wherein: the metallic terminal member is formed from a metallic sheet material and having an axially extending frame main body section, an element abutment section extending while being bent to change the direction of extension, from a front end of the frame main body section axially toward a rear end side of the frame main body section and contacting the electrode terminal section (30, 31, 32, 34, 36) of the detection element thereby being electrically connected thereto to form a current path, and a frame locking section (19, 219, 264, 314, 364, 414, 519) having a first locking surface (135, 235, 283, 333, 433) facing axially toward a rear end side of the frame main body section and a second locking surface (137, 237, 285, 335, 385, 435, 537) facing in the direction of an intervening space between the frame main body section and the element abutment section and toward the element abutment section; and the separator has a locking groove (90, 91) for disposition of the frame locking section and engages at an inner wall surface of the locking groove with the first locking surface and the second locking surface. a detection element in the form of an axially extending plate, having a front end side to face an object to be measured and formed with an electrode terminal section (30, 31, 32, 34, 36) at a rear end side; a separator made of an insulating material and having an element insertion hole accommodating the rear end side of the detection element; and a metallic terminal member interposed between the detection element and an inner surface of the element insertion hole of the separator; wherein: the metallic terminal member is formed from a metallic sheet material and having an axially extending frame main body section, an element abutment section extending while being bent to change the direction of extension, from a front end of the frame main body section axially toward a rear end side of the frame main body section and contacting the electrode terminal section (30, 31, 32, 34, 36) of the detection element thereby being electrically connected thereto to form a current path, and a frame locking section (19, 219, 264, 314, 364, 414, 519) having a first locking surface (135, 235, 283, 333, 433) facing axially toward a rear end side of the frame main body section and a second locking surface (137, 237, 285, 335, 385, 435, 537) facing in the direction of an intervening space between the frame main body section and the element abutment section and toward the element abutment section; and the separator has a locking groove (90, 91) for disposition of the frame locking section and engages at an inner wall surface of the locking groove with the first locking surface and the second locking surface. the metallic terminal member is formed from a metallic sheet material and having an axially extending frame main body section, an element abutment section extending while being bent to change the direction of extension, from a front end of the frame main body section axially toward a rear end side of the frame main body section and contacting the electrode terminal section (30, 31, 32, 34, 36) of the detection element thereby being electrically connected thereto to form a current path, and a frame locking section (19, 219, 264, 314, 364, 414, 519) having a first locking surface (135, 235, 283, 333, 433) facing axially toward a rear end side of the frame main body section and a second locking surface (137, 237, 285, 335, 385, 435, 537) facing in the direction of an intervening space between the frame main body section and the element abutment section and toward the element abutment section; and the separator has a locking groove (90, 91) for disposition of the frame locking section and engages at an inner wall surface of the locking groove with the first locking surface and the second locking surface.