An electromagnetic contactor includes a base plate having an aperture hole; an arc extinguishing chamber formed by a fixed terminal support insulating substrate and a cylinder portion; and a bottomed tubular cap in which one end thereof is open. An arc extinguishing chamber connection portion is formed by the arc extinguishing chamber and a first connection member having a flange portion. A cap connection portion is formed by the cap and a second connection member having a tube portion and a flange portion. The flange portion of the first connection member is attached to one surface of the base plate, and the flange portion of the second connection member is attached to the other surface of the base plate, so that the arc extinguishing chamber connection portion and the cap connection portion are in communication through the aperture hole of the base plate.