A method for preventing overheating of a microwave oven including a controller for controlling an output level of a magnetron, comprising: receiving information of cooking conditions and a cooking start command input by a user, the cooking conditions comprising a) receiving information of cooking conditions and a cooking start command input by a user, the cooking conditions comprising an output level of the magnetron for subsequent cooking; b) detecting a pausing period of time from a time of finishing preceding cooking to a time of starting the subsequent cooking if it is determined that the output level of the magnetron is greater than a preset output level thereof; and c) operating the microwave oven at the preset output level after changing the output level to the preset output level according to the detected pausing period. With this method, components of the microwave oven are effectively prevented from being overheated while maintaining cooking efficiency even when a short period of time is required for cooking.