PURPOSE: To provide a semiconductor device having high reliability even under high temperature and high moisture conditions by covering a semicoductor element and leads with resin composition which contains polytrifluoro ethoxyphosphagen.

CONSTITUTION: A semiconductor element and leads are covered with resin composition which contains at least polytrifluoroethoxyphosphagen or resin composition which contains at least polytrifluorophosphagen and heterocyclic polymer. The polytrifluoroethoxyphosphagen is polymer represented by a formula (I). The heterocyclic polymer includes polyimide, polybenzimidazole, polybenzoxysadiazothion. The sealing resin composition to be used includes, for example, epoxy resin, phenol resin, polyetheretherketone, polypropylene.