In a method of manufacturing a semiconductor package, information with respect to a downward warpage of a reference package substrate, which may be bent with respect to a long axis and/or a short axis of the reference package substrate in applying heat to the reference package substrate to which a plurality of semiconductor chips may be attached using a die attach film (DAF), may be obtained. A package substrate, which may include a first surface to which the semiconductor chips may be attached using the DAF and a second surface opposite to the first surface, may be rotated with respect to the long axis or the short axis at an angle selected based on the information. The heat may be applied to the package substrate to cure the DAF and correct a warpage of the package substrate. Thus, warpage of the package substrate may be corrected for.