A microwave irradiation system includes first and second microwave generators, and an applicator which includes: a microwave transmission part connected to the first and second microwave generators; a reflecting plane, at an other end of the microwave transmission part of the applicator, configured to reflect microwaves from the first and the second microwave generators at such a location that a space of an object, in the microwave transmission part of the applicator between the end and the other end is irradiated with both a greater intensity of electric field and a smaller intensity of magnetic field generated by the first microwave generator and with both a greater intensity of magnetic field and a smaller intensity of electric field generated by the second microwave generator; and a filter part through which at least one of the first and second microwave generators is connected to the applicator.