A microwave oven has a cooking chamber (20) for cooking a food using microwave energy, and a magnetron oscillator for producing microwave radiation to heat the food. The oven also includes a hole (21b) formed on an upper surface (21) of the cooking chamber and a lamp (41) for illuminating the cooking chamber through the hole. The lamp includes a filament (41a) and a bulb (41b), and the filament is located about 2mm above the upper surface (21). The hole, which is less than 19mm in diameter, is formed ²/₁₄th of the upper surface's depth from the front of the upper surface. The upper surface includes a beveled portion that slopes downward towards the front of the microwave oven in which the hole is formed. The lamp is located at the hole so as to face the rear of the cooking chamber and is covered by a protective glass cover (42) protruding into the cooking chamber.