A film sealant useful for tightly sealing an electric device at a low temperature and a sealing method of using the sealant are provided. The device is covered and sealed by covering at least a region of the device with a film sealant containing a copolyamide-series resin, heat-melting the sealant, and cooling the sealant. The copolyamide-series resin may have a melting point or softening point of 75 to 160° C. and may be a crystalline resin. The copolyamide-series resin may be a multiple copolymer or may contain a unit derived from a long-chain component having a C8-16alkylene group (e.g., a C9-17lactam and an aminoC9-17alkanecarboxylic acid). The film sealant may cover one side of the device.