Abstract: Disclosed are a method and a device for cooling a high voltage transformer for a microwave oven, in which the high voltage transformer is sealed so as to separate a coil and a core from the outside and to improve a cooling effect, and in which electric connection lines leading from the high voltage transformer are effectively treated and a fixed structure of a container for accommodating the high voltage transformer is improved so as to protect users of the high voltage transformer from dangers such as an electrical shock occurring in inspecting the microwave oven, thereby improving performance and quality of the microwave oven and the high voltage transformer.