A fermenter, a microwave oven including the fermenter, and a method of controlling the fermenter and microwave oven are provided. The fermenter includes a fermenter casing having one side open and defining a fermenting chamber, a fermenter door that selectively opens or closes the fermenting chamber, a thermoelectric element that applies heat to the fermenting chamber or absorbs heat from the fermenting chamber, and a current switching device that converts current supplied to the thermoelectric element such that the thermoelectric element absorbs or generates heat. The fermenter may be very conveniently employed and a microwave oven with various functions may also be provided.
