An ion exchange membrane electrolyzer comprises electrodes at least either of which is held in contact with leaf springs formed integrally with a leaf spring holding member arranged in an electrode chamber so as to extend toward the electrode and remain electrically energized at the respective electrode touching sections thereof, each of the leaf springs having a crooked section arranged at a position separated from its connecting section connecting itself to the leaf spring holding member and adapted to be bent toward the leaf spring holding member when the electrode touching section is pressed toward the leaf spring holding member side.