A microwave oven includes a housing having a receiving chamber therein. An inner case is provided in the receiving chamber. A left air channel is formed between a left side wall of the receiving chamber and a left side of the inner case, a right air channel is formed between a right side wall of the receiving chamber and a right side of the inner case. Respective fans are provided in the left and right air channels, each of the left and right fans including a front impeller, a rear impeller and a driving motor. At least one of the front and rear impellers is adjacent to at least one of front and rear walls of the receiving chamber which is corresponding thereto, at least one of the front and rear impellers is spaced from the driving motor at a predetermined distance.