An over-the-range (OTR) microwave oven includes a main body installed above a cooking source of a gas range and has therein a cavity and an electric equipment chamber in which a magnetron is located. An air exhaust path is installed inside the main body and provides a path through which air generated from the cooking source which is introduced through a suction port formed at the bottom of the main body by a suction force of a blower installed at the main body is exhausted to the outside of the main body. An airstream guide path is installed inside the main body and provides a path through which air inside the electric equipment chamber is discharged to a front end portion of the bottom of the main body by a flow generating apparatus installed inside the electric equipment chamber in order to guide air from the cooking source to the suction port, so that delightfulness of a cooking environment is obtained by blocking air containing cooking by-products which used to flow toward the face of the cook, thereby improving product reliability and competitiveness.