A microwave oven is provided to permit foodstuff to be uniformly cooked in each part in a cooking chamber, by controlling the length of stay of a tray at the leftmost area or the rightmost area of motion range. A microwave oven comprises a cooking chamber(10) having a bottom plate(12); a tray(50) linearly moving in the cooking chamber; a motor(60) for providing power for movement of the tray; a support member(70) interposed between the bottom plate and the tray so as to support the tray; and a motion transfer unit for transferring power of the motor to the support member in a manner that the support member linearly moves. The support member has a center where a guide hole(71) is formed for guiding linear motion of the support member. The motion transfer unit moves within the guide hole, and contacts an inner surface of the guide hole such that the support member linearly moves in left and right directions.
