PURPOSE: To enable liquid item to be heated and cooked at a uniform temperature state by a method wherein in the case that the item is liquid, an opening adjusting means is controlled in such a manner that a supplying amount of microwave from a lower opening is high and an amount of supplying microwave from a lower opening is low or becomes zero.

CONSTITUTION: In the case that item is liquid, a microwave supplying and controlling means controls opening control means 17 and 16 in such a manner that a supplying amount of microwave from a lower opening 7 within a heating and cooking chamber 3 is high and an amount of supplying microwave from an upper opening 6 is low or becomes 0. With such an arrangement as above, the lower part of the heated and cooked item is heated in particular. Accordingly, a natural convection of liquid is promoted and the items are uniformly heated at their upper part and lower part, respectively. With such an arrangement as above, in the case that the liquid item is heated, it is possible to heat the liquid uniformly.