Microwave oven including a base plate (100), a front plate (110) and a rear plate (130) vertically mounted at front and rear edges of the base plate (100), an inner case (200) between the front plate (110) and the rear plate (130) having a curved rear part to form a cooking chamber (200a) therein, an outfit chamber (400) at one side of the inner case (200) having various components such as a magnetron (410) and fan (430) mounted therein, and a convection part (300)mounted in rear of the inner case (200) for providing heat to the cooking chamber (200a), thereby providing a microwave oven which has a good performance even with a small size.