A defrost vessel for a microwave oven includes a body having a certain space therein for receiving a refrigerating load, and an antenna connected to the body for oscillating a microwave into the space of the body. When microwave is supplied into a cavity of the microwave oven, the microwave is oscillated into the space of the body by the antenna and thus the microwave is deeply penetrated up to inside of the refrigerating load. Also, the microwave is secondly emitted into the space of the body from an edge of the slot, thereby completely defrosting the refrigerating load.