A sensor element, comprising: a thermosensitive body; a pair of conductive wires electrically connected to the thermosensitive body; and a first covering layer made of a first electrical insulator, the first covering layer covering the thermosensitive body, wherein: the pair of conductive wires include first regions that are connected to the thermosensitive body and include a small mutual distance, second regions that are respectively connected to the first regions and include a mutual distance continuously expanded, and third regions that are respectively connected to the second regions and include a mutual distance larger than the mutual distance of the first regions, conductors are exposed in all of the first regions, the second regions, and the third regions, each conductive wire comprises an extraction wire and a lead wire, each extraction wire comprising one of the first regions, one of the second regions and one of the third regions, and each third region being connected with one respective lead wire, and the first covering layer covers the first region and the second region of each extraction wire, characterized in that each extraction wire is independently covered with the first covering layer in the second region such that the first covering layer has a shape that widens a mutual gap between the extraction wires in the second regions resulting in the creepage distance between the second regions being greater than the minimum distance between the third regions. a thermosensitive body; a pair of conductive wires electrically connected to the thermosensitive body; and a first covering layer made of a first electrical insulator, the first covering layer covering the thermosensitive body, wherein: the pair of conductive wires include first regions that are connected to the thermosensitive body and include a small mutual distance, second regions that are respectively connected to the first regions and include a mutual distance continuously expanded, and third regions that are respectively connected to the second regions and include a mutual distance larger than the mutual distance of the first regions, conductors are exposed in all of the first regions, the second regions, and the third regions, each conductive wire comprises an extraction wire and a lead wire, each extraction wire comprising one of the first regions, one of the second regions and one of the third regions, and each third region being connected with one respective lead wire, and the first covering layer covers the first region and the second region of each extraction wire, the pair of conductive wires include first regions that are connected to the thermosensitive body and include a small mutual distance, second regions that are respectively connected to the first regions and include a mutual distance continuously expanded, and third regions that are respectively connected to the second regions and include a mutual distance larger than the mutual distance of the first regions, conductors are exposed in all of the first regions, the second regions, and the third regions, each conductive wire comprises an extraction wire and a lead wire, each extraction wire comprising one of the first regions, one of the second regions and one of the third regions, and each third region being connected with one respective lead wire, and the first covering layer covers the first region and the second region of each extraction wire, characterized in that each extraction wire is independently covered with the first covering layer in the second region such that the first covering layer has a shape that widens a mutual gap between the extraction wires in the second regions resulting in the creepage distance between the second regions being greater than the minimum distance between the third regions.