A high degree of resistance to moisture and solder and high flame retardancy are realized without incorporating a halogen in view of environmental friendliness. A phenolic resin has structural moieties which are a naphthylmethyloxy group- or anthrylmethyloxy group-containing aromatic hydrocarbon group (ph1), a phenolic hydroxyl group-containing aromatic hydrocarbon group (ph2), and a divalent aralkyl group (X) represented by general formula (1) below: (where Ar represents a phenylene group or a biphenylene group and Rs each independently represent a hydrogen atom or a methyl group) and has a structure in which plural aromatic hydrocarbon groups selected from the group consisting of the naphthylmethyloxy group- or anthrylmethyloxy group-containing aromatic hydrocarbon group (ph1) and the phenolic hydroxyl group-containing aromatic hydrocarbon group (ph2) are bonded through the divalent aralkyl group (X). This phenolic resin is used as a curing agent for an epoxy resin.