Abstract: A container mouth (21) is sealed with an inner seal which comprises a reseal liner (9) fitted inside of a cap (23) and a seal cover (10) separably laminated to the reseal liner and remaining on the container mouth after the container (20) is uncapped. The seal cover comprises a metal foil (5), a glassine paper (7) layered on the underside of the metal foil, and a hot-melt adhesive layer (8) coated on the underside of the glassine paper by gravure roll coating process. A polyethlene film (6) is preferably layered between the metal foil and the glassine paper to provide a better peel-off strength therebetween. The glassine paper may be replaced with an easy-peelable plastic film, such as a PET (polyethlene terephthalate resin) film. The inner seal fitted in the cap is placed onto the container mouth, and then the cap is subjected to a high frequency of 20-600 KHz to melt the hot-melt adhesive layer, whereby the seal cover hermetically seals the container mouth.