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 includes an axially extending frame main body section (12, 262), an element abutment section (16, 266) extending while being bent to change the direction of extension, from a front end of the frame main body section (12, 262) axially toward a rear end side of the frame main body section (12, 262) 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, 264) provided to a portion of the frame main body section (12, 262) and having a larger width than a remaining portion of the frame main body section (12, 262); and the metallic terminal member is disposed within the separator so as to be put in a state of being engaged at the frame locking section (19, 264) with the separator, characterized in that the frame locking section (19, 264) has an extension portion (131, 133, 271, 273) that extends in the direction apart from the element abutment section (16, 266) and is bent at least once or more at an intermediate part thereof in a way as to change the direction of extension, the frame locking section (19, 264) being larger in width than the remaining portion of the frame main body section (12, 262) when the extension portion (131, 133, 271, 273) is developed in the width direction of the remaining portion of the frame main body section (12, 262). 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 includes an axially extending frame main body section (12, 262), an element abutment section (16, 266) extending while being bent to change the direction of extension, from a front end of the frame main body section (12, 262) axially toward a rear end side of the frame main body section (12, 262) 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, 264) provided to a portion of the frame main body section (12, 262) and having a larger width than a remaining portion of the frame main body section (12, 262); and the metallic terminal member is disposed within the separator so as to be put in a state of being engaged at the frame locking section (19, 264) with the separator, characterized in that the frame locking section (19, 264) has an extension portion (131, 133, 271, 273) that extends in the direction apart from the element abutment section (16, 266) and is bent at least once or more at an intermediate part thereof in a way as to change the direction of extension, the frame locking section (19, 264) being larger in width than the remaining portion of the frame main body section (12, 262) when the extension portion (131, 133, 271, 273) is developed in the width direction of the remaining portion of the frame main body section (12, 262).