An adhesive sheet is attached to a package substrate having a through hole so that an ultraviolet (UV) curable resin layer of the adhesive sheet faces the package substrate. Light is then radiated to the UV curable resin layer through the through hole in order to cure the exposed part of the UV curable resin layer. The cured part of the UV curable resin layer is removed together with a base film of the adhesive sheet. A glass plate is then attached to the UV curable resin remaining on the package substrate. Light is then radiated to bond the glass plate to the package substrate.