A metal lid for use in hermetic sealing of a semiconductor package comprises a lid body comprising a metal plate having a solder layer secured to the entire surface of the metal lid by cladding. The lid is placed in position on a substrate and can seal the resulting package by heating to melt the solder layer. The lid can be readily mass-produced and can seal the package with high seal reliability and without deposition of solder balls on the inner wall of the package.