A resin composition comprising: a chelating flux agent; a thermal radical polymerization initiator; and a radical polymerizable compound, wherein a content of the chelating flux agent in the resin composition is 5 parts by mass or more and 50 parts by mass or less based on 100 parts by mass of a total amount of the radical polymerizable compound, wherein the chelating flux agent comprises a compound represented by the following formula and/or an imine compound represented by the following formula: wherein Q is an arylene group, an alkylene group, an alkenylene group, a cycloalkylene group, a cycloalkenylene group, a heterocyclylene group or a heteroarylene group; R 1 and R 2 are each independently a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group or a hexyl group; R 3 and R 4 are each independently an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group or a heterocyclyl group; and for the arylene group; and for the arylene group, the alkylene group, the alkenylene group, the cycloalkylene group, the cycloalkenylene group, the heterocyclylene group, the heteroarylene group, the alkyl group, the cycloalkyl group, the aryl group and the heteroaryl group, a hydrogen atom bonded to the group is optionally substituted with a hydroxy group or a mercapto group; and wherein R 5 is a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group or a hexyl group; R 6 and R 7 are each independently an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group or a heterocyclyl group; and for the alkyl group, the cycloalkyl group, the aryl group, the heteroaryl group and the heterocyclyl group, a hydrogen atom bonded to the group is optionally substituted with a hydroxy group or a mercapto group, and wherein the radical polymerizable compound comprises: a maleimide compound represented by the following formula, and at least one maleimide compound(s) selected from the group consisting of 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, a maleimide compound represented by the following formula, and a maleimide compound represented by the following formula: wherein each R 8 independently represents a hydrogen atom or a methyl group, and n 1 represents an integer of 1 or more; wherein an average value of n 2 is 1 or more and 30 or less; and wherein R 9 and R 10 each independently represent a hydrogen atom, a methyl group or an ethyl group, and each R 11 independently represents a hydrogen atom or a methyl group. a chelating flux agent; a thermal radical polymerization initiator; and a radical polymerizable compound, wherein a content of the chelating flux agent in the resin composition is 5 parts by mass or more and 50 parts by mass or less based on 100 parts by mass of a total amount of the radical polymerizable compound, wherein the chelating flux agent comprises a compound represented by the following formula and/or an imine compound represented by the following formula: wherein Q is an arylene group, an alkylene group, an alkenylene group, a cycloalkylene group, a cycloalkenylene group, a heterocyclylene group or a heteroarylene group; R 1 and R 2 are each independently a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group or a hexyl group; R 3 and R 4 are each independently an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group or a heterocyclyl group; and for the arylene group; and for the arylene group, the alkylene group, the alkenylene group, the cycloalkylene group, the cycloalkenylene group, the heterocyclylene group, the heteroarylene group, the alkyl group, the cycloalkyl group, the aryl group and the heteroaryl group, a hydrogen atom bonded to the group is optionally substituted with a hydroxy group or a mercapto group; and wherein R 5 is a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group or a hexyl group; R 6 and R 7 are each independently an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group or a heterocyclyl group; and for the alkyl group, the cycloalkyl group, the aryl group, the heteroaryl group and the heterocyclyl group, a hydrogen atom bonded to the group is optionally substituted with a hydroxy group or a mercapto group, and wherein the radical polymerizable compound comprises: a maleimide compound represented by the following formula, and at least one maleimide compound(s) selected from the group consisting of 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, a maleimide compound represented by the following formula, and a maleimide compound represented by the following formula: a maleimide compound represented by the following formula, and at least one maleimide compound(s) selected from the group consisting of 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, a maleimide compound represented by the following formula, and a maleimide compound represented by the following formula: wherein each R 8 independently represents a hydrogen atom or a methyl group, and n 1 represents an integer of 1 or more; wherein an average value of n 2 is 1 or more and 30 or less; and wherein R 9 and R 10 each independently represent a hydrogen atom, a methyl group or an ethyl group, and each R 11 independently represents a hydrogen atom or a methyl group.