An epoxy resin composition for semiconductor encapsulation which comprises (A) a crystalline epoxy resin, (B) a phenol resin represented by the general formula (1), wherein R1 and R2 are each independently hydrogen or alkyl having 1 to 4 carbon atoms and R1's or R2's may be the same or different from each other; a is an integer of 0 to 4; b is an integer of 0 to 4; c is an integer of 0 to 3; and n is a number of 0 to 10 on average, (C) a (co)polymer comprising structural units derived from butadiene or a derivative of the (co)polymer, and (D) 80 to 95% by weight of an inorganic filler based on the composition.