An epoxy resin composition comprising an epoxy resin and organic fine particles, the organic fine particles being polyolefin resin fine particles, and the epoxy resin being at least one epoxy resin selected from the group consisting of: an epoxy resin represented by the formula (1-iia): wherein X ii is a divalent group obtained by removing two hydrogen atoms from a saturated hydrocarbon ring or an unsaturated hydrocarbon ring, or from rings having a structure in which 2 to 6 saturated hydrocarbon rings and/or unsaturated hydrocarbon rings are condensed; or a divalent group represented by the formula (2 g -iia): wherein Y is a bond, a C 1-6 alkylene group that may be substituted with a C 1-4 alkyl group, an oxygen atom (-O-), a sulfur atom (-S-), -SO-, or -SO 2 -; R 1 is the same or different, and is a C 1-18 alkyl group, a C 2-9 alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, wherein one or more carbon atoms of these groups may be replaced by at least one atom selected from the group consisting of an oxygen atom and a nitrogen atom; R 2 is the same or different, and is a C 1-18 alkylene group, wherein one or more carbon atoms of this group other than a carbon atom directly bonded to a silicon atom may be replaced by at least one atom selected from the group consisting of an oxygen atom and a nitrogen atom; R 3 is the same or different, and is a C 1-18 alkyl group, a C 2-9 alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, wherein one or more carbon atoms of these groups may be replaced by at least one atom selected from the group consisting of an oxygen atom and a nitrogen atom; m is an integer of 0 to 6; and n is an integer of 0 to 3; and an epoxy resin represented by the formula (1-iiia): wherein X iii is a trivalent group obtained by removing three hydrogen atoms from a saturated hydrocarbon ring or an unsaturated hydrocarbon ring, or from rings having a structure in which 2 to 6 saturated hydrocarbon rings and/or unsaturated hydrocarbon rings are condensed; or a trivalent group represented by the formula (2 g -iiia): wherein Y is as defined above; and R 1, R 2, R 3, m, and n are as defined above. the organic fine particles being polyolefin resin fine particles, and the epoxy resin being at least one epoxy resin selected from the group consisting of: an epoxy resin represented by the formula (1-iia): wherein X ii is a divalent group obtained by removing two hydrogen atoms from a saturated hydrocarbon ring or an unsaturated hydrocarbon ring, or from rings having a structure in which 2 to 6 saturated hydrocarbon rings and/or unsaturated hydrocarbon rings are condensed; or a divalent group represented by the formula (2 g -iia): wherein Y is a bond, a C 1-6 alkylene group that may be substituted with a C 1-4 alkyl group, an oxygen atom (-O-), a sulfur atom (-S-), -SO-, or -SO 2 -; an epoxy resin represented by the formula (1-iia): wherein X ii is a divalent group obtained by removing two hydrogen atoms from a saturated hydrocarbon ring or an unsaturated hydrocarbon ring, or from rings having a structure in which 2 to 6 saturated hydrocarbon rings and/or unsaturated hydrocarbon rings are condensed; or a divalent group represented by the formula (2 g -iia): wherein Y is a bond, a C 1-6 alkylene group that may be substituted with a C 1-4 alkyl group, an oxygen atom (-O-), a sulfur atom (-S-), -SO-, or -SO 2 -; R 1 is the same or different, and is a C 1-18 alkyl group, a C 2-9 alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, wherein one or more carbon atoms of these groups may be replaced by at least one atom selected from the group consisting of an oxygen atom and a nitrogen atom; R 2 is the same or different, and is a C 1-18 alkylene group, wherein one or more carbon atoms of this group other than a carbon atom directly bonded to a silicon atom may be replaced by at least one atom selected from the group consisting of an oxygen atom and a nitrogen atom; R 3 is the same or different, and is a C 1-18 alkyl group, a C 2-9 alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, wherein one or more carbon atoms of these groups may be replaced by at least one atom selected from the group consisting of an oxygen atom and a nitrogen atom; m is an integer of 0 to 6; and n is an integer of 0 to 3; and an epoxy resin represented by the formula (1-iiia): wherein X iii is a trivalent group obtained by removing three hydrogen atoms from a saturated hydrocarbon ring or an unsaturated hydrocarbon ring, or from rings having a structure in which 2 to 6 saturated hydrocarbon rings and/or unsaturated hydrocarbon rings are condensed; or a trivalent group represented by the formula (2 g -iiia): wherein Y is as defined above; and an epoxy resin represented by the formula (1-iiia): wherein X iii is a trivalent group obtained by removing three hydrogen atoms from a saturated hydrocarbon ring or an unsaturated hydrocarbon ring, or from rings having a structure in which 2 to 6 saturated hydrocarbon rings and/or unsaturated hydrocarbon rings are condensed; or a trivalent group represented by the formula (2 g -iiia): wherein Y is as defined above; and R 1, R 2, R 3, m, and n are as defined above.