A sensor includes a detector element, a connection terminal, and a separator. The contacting portion is in contact with a conductive member so as to overlap the conductive member in a thickness direction, which is a direction of thickness of the detector element between the principal surfaces. The separator includes an element accommodation space that accommodates a portion of an element contact portion and an element back portion, and a partition wall that separates the element accommodation space from a terminal accommodation space that accommodates the contacting portion and a portion of the conductive member and that is adjacent to the element accommodation space in the thickness direction. A frame main body is disposed in an element-side region, which is a region on an element-accommodation-space side in the thickness direction in a region obtained by extending the terminal accommodation space toward the front side in the axial direction.