A connection portion of a lead wire is close to a surface of a metal plate, held at an accurate position, and held while preventing the wire from being movable. A connection structure of the lead wire includes the metal plate, the lead wire connected to the surface of the metal plate, and a pair of holding protrusions. The holding protrusions sandwich at least two parts of the lead wire to dispose the lead wire at a fixed position. Each of the holding protrusions has a holding gap sandwiching and holding the press-fitted lead wire. A connection space of the lead wire and the metal plate is provided between the holding protrusions. The lead wire is held on the surface of the metal plate with the holding protrusions and is connected to the surface of the metal plate in the connection space.