There is disclosed an encapsulating epoxy resin composition, containing an epoxy resin (A), a curing agent (B), and a composite metal hydroxide (C), and having a disk flow greater than or equal to 80mm. The resin composition is preferably applied for encapsulating a semiconductor device having at least one of features including: (a) at least one of an encapsulating material of an upper side of a semiconductor chip and an encapsulating material of a lower side of the semiconductor chip has a thickness less than or equal to 0.7 mm; (b) a pin count is greater than or equal to 80; (c) a wire length is greater than or equal to 2 mm; (d) a pad pitch on the semiconductor chip is less than or equal to 90 (m; (e) a thickness of a package, in which the semiconductor chip is disposed on a mounting substrate, is less than or equal to 2mm; and (f) an area of the semiconductor chip is greater than or equal to 25 mm<2>.