An outdoor heat exchanger that is used in a heat pump-type vehicle air conditioner switchable between cooling operation and heating operation and that exchanges heat between a refrigerant and outdoor air, the outdoor air heat exchanger comprising: flat tubes in which the refrigerant flows, the flat tubes having a cross-sectional shape extended in a first direction, the flat tubes being arranged in a second direction orthogonal to the first direction so as to face each other, wherein the outdoor air is caused to flow between the flat tubes from one side to the other in the first direction; and a corrugated fin disposed between the flat tubes adjacent to each other, the corrugated fin comprising: a plurality of plate portions arranged in a third direction orthogonal to the first direction and the second direction; and a plurality of folded portions joined alternately to the flat tubes adjacent to each other, wherein each of the plurality of plate portions has a plurality of louvers formed by cutting and raising, the plurality of louvers being inclined with respect to the first direction and being substantially continuous with each other in the first direction, each of the plurality of plate portions has an extension portion projecting windward in the first direction from a joining region where the plurality of folded portions are joined to the flat tubes, a foremost louver that is located on the most windward side among the plurality of louvers is disposed entirely within the extension portion, each of the plurality of plate portions has a front flat portion as a part of the extension portion, the front flat portion being located windward of the foremost louver, characterized in that the front flat portion has an area larger than half of that of the extension portion, and the entire foremost louver is disposed leeward of a center of the extension portion in the first direction. flat tubes in which the refrigerant flows, the flat tubes having a cross-sectional shape extended in a first direction, the flat tubes being arranged in a second direction orthogonal to the first direction so as to face each other, wherein the outdoor air is caused to flow between the flat tubes from one side to the other in the first direction; and a corrugated fin disposed between the flat tubes adjacent to each other, the corrugated fin comprising: a plurality of plate portions arranged in a third direction orthogonal to the first direction and the second direction; and a plurality of folded portions joined alternately to the flat tubes adjacent to each other, wherein each of the plurality of plate portions has a plurality of louvers formed by cutting and raising, the plurality of louvers being inclined with respect to the first direction and being substantially continuous with each other in the first direction, each of the plurality of plate portions has an extension portion projecting windward in the first direction from a joining region where the plurality of folded portions are joined to the flat tubes, a foremost louver that is located on the most windward side among the plurality of louvers is disposed entirely within the extension portion, each of the plurality of plate portions has a front flat portion as a part of the extension portion, the front flat portion being located windward of the foremost louver, characterized in that the front flat portion has an area larger than half of that of the extension portion, and the entire foremost louver is disposed leeward of a center of the extension portion in the first direction.