An electromagnetic contactor has a pair of fixed contacts; a movable contact disposed to be capable of contacting with and separating from the pair of fixed contacts; and an electromagnetic unit driving the movable contact. The electromagnetic unit has a magnetic yoke having an open upper part; an upper magnetic yoke cross-linked in the open upper part of the magnetic yoke; a spool having a central opening in which an exciting coil is wound around the spool; a movable plunger movably disposed in the central opening of the spool in an axial direction and having a tip end protruding, the movable plunger urged by a return spring; and an auxiliary yoke forming a magnetic path between the movable plunger and the U-shaped magnetic yoke when the movable plunger is in an open position. The movable plunger is coupled to the movable contact through a coupling shaft.