Abstract: An electromagnetic wave energy seal for a microwave oven comprises a .lambda.g/4 choke seal including an internal plate for forming a first capacitive seal, an external plate for forming a recessed chamber with an external plate, a stepped portion having a vertical portion, slots formed with predetermined periodical intervals, a bent portion for forming a second capacitive seal, and a choke cover for blocking the opening of the recessed chamber, whereby the radio frequency leakage can be perfectly prevented from a heat cavity of the microwave oven and the thickness of a door of the microwave oven can be reduced.