A microwave heating device includes a microwave generating portion outputting a microwave, a conductive heating chamber into which the microwave is led and having a short-circuited terminal end in a traveling direction of the microwave, and a tuner provided between the microwave generating portion and the heating chamber. The heating chamber has an opening for passing a member to be heated therethrough. The tuner re-reflects the microwave reflected at the terminal end of the heating chamber onto the heating chamber side. The microwave output end of the microwave generating portion and the tuner are connected by a square tubular waveguide made of a conductive material. The tuner and the terminal end of the heating chamber are connected by a square tubular waveguide, which is made of a conductive material except for the opening for passing the member to be heated therethrough.