A microwave cooker comprises a body having a cooking chamber therein, the cooking chamber having one opened side, a microwave source disposed at the body for supplying microwave to the cooking chamber, a door coupled to the body for opening and closing the cooking chamber, and a multi-stage choke seal formed at the door, having different resonant frequencies at a frequency region higher than a central frequency of microwave, and having different LC resonant circuits for preventing the microwave from being leaked between the body and the door.