A thermally conductive material-forming composition comprising: an epoxy compound; one or more kinds of phenolic compounds selected from the group consisting of a compound represented by General Formula and a compound represented by General Formula; and an inorganic substance, in General Formula, m1 represents an integer of 0 or greater; n1 and n2 each independently represent an integer of 2 or greater; L 1 represents -C(R 2)(R 3)- or -CO-; L 2 represents -C(R 4)(R 5)- or -CO-; Ar 1 and Ar 2 each independently represent a benzene ring group or a naphthalene ring group; R 1 and R 6 each independently represent a hydrogen atom, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkyl group, an alkoxy group, or an alkoxycarbonyl group; R 2 to R 5 each independently represent a hydrogen atom, a hydroxyl group, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkyl group, an alkoxy group, or an alkoxycarbonyl group; Q a represents a hydrogen atom, an alkyl group, a phenyl group, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkoxy group, or an alkoxycarbonyl group; and in a case where there are a plurality of L 2 's and Q a 's, the plurality of L 2 's may be the same as or different from each other and the plurality of Q a 's may be the same as or different from each other, and in a case where m1 represents 0, L 1 represents -CH - or -CO-; and in General Formula, m2 represents an integer of 0 or greater; n1 and n2 each independently represent an integer of 2 or greater; R 1 and R 6 each independently represent a hydrogen atom, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkyl group, an alkoxy group, or an alkoxycarbonyl group; R 7 represents a hydrogen atom or a hydroxyl group; Q b represents a hydrogen atom, an alkyl group, a phenyl group, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkoxy group, or an alkoxycarbonyl group; and in a case where there are a plurality of R 7 's and Q b 's, the plurality of R 7 's may be the same as or different from each other and the plurality of Q b 's may be the same as or different from each other. an epoxy compound; one or more kinds of phenolic compounds selected from the group consisting of a compound represented by General Formula and a compound represented by General Formula; and an inorganic substance, in General Formula, m1 represents an integer of 0 or greater; n1 and n2 each independently represent an integer of 2 or greater; L 1 represents -C(R 2)(R 3)- or -CO-; L 2 represents -C(R 4)(R 5)- or -CO-; Ar 1 and Ar 2 each independently represent a benzene ring group or a naphthalene ring group; R 1 and R 6 each independently represent a hydrogen atom, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkyl group, an alkoxy group, or an alkoxycarbonyl group; R 2 to R 5 each independently represent a hydrogen atom, a hydroxyl group, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkyl group, an alkoxy group, or an alkoxycarbonyl group; Q a represents a hydrogen atom, an alkyl group, a phenyl group, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkoxy group, or an alkoxycarbonyl group; and in a case where there are a plurality of L 2 's and Q a 's, the plurality of L 2 's may be the same as or different from each other and the plurality of Q a 's may be the same as or different from each other, and in a case where m1 represents 0, L 1 represents -CH - or -CO-; and in General Formula, m2 represents an integer of 0 or greater; n1 and n2 each independently represent an integer of 2 or greater; R 1 and R 6 each independently represent a hydrogen atom, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkyl group, an alkoxy group, or an alkoxycarbonyl group; R 7 represents a hydrogen atom or a hydroxyl group; Q b represents a hydrogen atom, an alkyl group, a phenyl group, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkoxy group, or an alkoxycarbonyl group; and in a case where there are a plurality of R 7 's and Q b 's, the plurality of R 7 's may be the same as or different from each other and the plurality of Q b 's may be the same as or different from each other.