Epoxy resin composition

An epoxy resin composition, comprising:

• a polyol (A) having a hydroxyl value of 130 to 600 mgKOH/g and a number average molecular weight of 100 or more and less than 1000;
• an epoxy resin (B);
• an amine curing agent (C);
• and
• a toughener (D),
• wherein:
• the amine curing agent (C) is at least one selected from an alicyclic amine, an amine having an ether bond, and an imidazole,
• the toughener (D) is at least one selected from the group consisting of a core shell polymer containing a core layer and a shell layer grafted on the core layer, a butadiene-acrylonitrile copolymer having a carboxyl group at a terminal, and a polyalkyleneoxide having an allyl group at a terminal,
• the core layer of the core shell polymer has a glass transition temperature of 0° C. or less,
• the epoxy resin composition contains the amine curing agent (C) in an amount of 5 parts by weight or more and 100 parts by weight or less, per 100 parts by weight of the epoxy resin (B), and the epoxy resin composition satisfies the following numerical formulas (1) and (2):
• 0.1≤Wt2/Wp≤8.0 (1)
• 0.1≤Wp≤8.0 (2)
• where Wp represents the polyol (A) content of the composition in % by weight and Wt represents the toughener (D) content of the composition in % by weight, both relative to a total amount of the polyol (A), the epoxy resin (B), the amine curing agent (C), and the toughener (D).