A motor fan for a vacuum cleaner, comprising: a motor mount configured to accommodate a motor part; an impeller located vertically above the motor part and configured to be rotated by the motor part; a diffuser located between the impeller and a motor body part; an impeller cover disposed vertically above the motor mount and configured to cover at least the diffuser and the impeller, the impeller cover defining an air inlet at an upper central portion of the impeller cover; an air discharge opening configured to discharge air that is suctioned through the air inlet and pressurized by the impeller; and a cooling flow path outlet being in fluid communication with an inner space of the motor mount and a space defined between the impeller and the air discharge opening, wherein the cooling flow path outlet is configured to discharge air from the inner space of the motor mount toward the space that is defined between the impeller and the air discharge opening, wherein the space defined between the impeller and the air discharge opening has a lower pressure than the inner space of the motor mount, and wherein the diffuser body defines the cooling flow path outlet; characterized in that: the diffuser includes a diffuser body and a vane located on an outer surface of the diffuser body, wherein the diffuser body includes: an inclined portion facing toward the impeller and being inclined downward with respect to the impeller, and a cylindrical portion extending downward from an outer edge of the inclined portion, and wherein the inclined portion defines the cooling flow path outlet, and the cylindrical portion defines the vane. a motor mount configured to accommodate a motor part; an impeller located vertically above the motor part and configured to be rotated by the motor part; a diffuser located between the impeller and a motor body part; an impeller cover disposed vertically above the motor mount and configured to cover at least the diffuser and the impeller, the impeller cover defining an air inlet at an upper central portion of the impeller cover; an air discharge opening configured to discharge air that is suctioned through the air inlet and pressurized by the impeller; and a cooling flow path outlet being in fluid communication with an inner space of the motor mount and a space defined between the impeller and the air discharge opening, wherein the cooling flow path outlet is configured to discharge air from the inner space of the motor mount toward the space that is defined between the impeller and the air discharge opening, wherein the space defined between the impeller and the air discharge opening has a lower pressure than the inner space of the motor mount, and wherein the diffuser body defines the cooling flow path outlet; characterized in that: the diffuser includes a diffuser body and a vane located on an outer surface of the diffuser body, wherein the diffuser body includes: an inclined portion facing toward the impeller and being inclined downward with respect to the impeller, and a cylindrical portion extending downward from an outer edge of the inclined portion, and wherein the inclined portion defines the cooling flow path outlet, and the cylindrical portion defines the vane. the diffuser includes a diffuser body and a vane located on an outer surface of the diffuser body, wherein the diffuser body includes: an inclined portion facing toward the impeller and being inclined downward with respect to the impeller, and a cylindrical portion extending downward from an outer edge of the inclined portion, and wherein the inclined portion defines the cooling flow path outlet, and the cylindrical portion defines the vane.