Epoxy resin composition and electronic component device

An epoxy resin composition, comprising:

• (A) an epoxy resin including a compound represented by the following Formula (I);
• (B) a phenol resin including a compound represented by the following Formula (II);
• and
• (C) a dihydroxynaphthalene compound including a compound represented by the following Formula (III):
• wherein, in the Formula (I), R represents a hydrogen atom, and n represents an integer from 0 to 10;
• wherein, in the Formula (II), R1 represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, or an alkoxy group having 1 or 2 carbon atoms, and each R1 may be the same as or different from another R1, and n represents an integer from 0 to 10;
• wherein, in the Formula (III), R1 represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, or an alkoxy group having 1 or 2 carbon atoms, and
• wherein a content of a total amount of the compound represented by Formula (III) with respect to a total amount of the compound represented by Formula (II) and the compound represented by Formula (III) is from 10% by mass to 55% by mass.