To provide a microwave oven that can reduce the cost of production by using a small diameter winding due to efficiently emanating heat and that can not only increase the volume of kitchen by expanding the kitchen till a portion region of the rear surface of an operation panel and reducing the mounting height of a high voltage transformer, but also efficiently exhaust heat from parts into an outside.

In a microwave oven comprising a body casing 5 forming a kitchen, a casing surrounding the body casing at a predetermined space, and a magnetron 53 supplying high frequency to the kitchen, it is characterized in that it comprises high voltage transformers 31, 41 connected in series each other for dividing and inputting a power supply from the outside power supply and dividing and outputting a driving voltage to a magnetron, wherein the transformers is arranged between the upper part of the body casing and the casing.