An exhaust gas flow regulator and a heat recovery steam generator including the same are provided. The exhaust gas flow regulator includes a plurality of first tubes spaced apart from each other in a vertical direction, a support plate disposed in a direction perpendicular to the extension direction of the first tubes and through which the plurality of first tubes penetrates, and a second tube disposed at one or both ends of the support plate so as to be coupled to the support plate and extending parallel to the first tubes, wherein the second tube is provided with a guide plate disposed to redirect exhaust gases flowing adjacent to the second tube toward the first tube.