A latch board of a microwave oven is provided. The latch board includes a first lever for controlling on/off operation of a monitor switch. The first lever is formed in an approximate triangular shape and has a hinge formed at a first edge, a pressing part formed at a second edge to come in contact with the monitor switch, and a protrusion part formed at a third edge to come in contact with the latch more rapidly. In the latch board, a difference in operation time of the monitor switch and the circuit switch can be increased such that the operation stability of the microwave oven is improved.