PURPOSE: To obtain a microwave oven applicable to high temperature quick heating by arranging a waveguide in the cylindrical side wall of a metal housing and arranging a heating muff of a microwave-absorbing material through a plurality of layers of a thermally insulative microwave-transparent material.

CONSTITUTION: A metal housing 10 is open at one end 12 and has a cylindrical side wall 16 into which a waveguide 18 coupled to a microwave generator 20 opens. A first outer layer 26 of a thermal insulative, microwave-transparent material abut against the inner side face of the cylindrical side wall 16. A second inner layer 28 of a thermal insulative microwave-transparent material having a central opening 30 abuts against the inner side face of the first outer layer 26. Furthermore, a muff of a microwave-absorbing material is received within the central opening 30. Open end of the metal housing 10 is closed by a metal plate 38. The microwave opening is entirely contained in a support 44 having a heat insulating lining 46.