Thermosetting resin compositions for manufacturing circuit boards and build-up circuit boards, and build-up boards, and multilayer bodies and circuit boards manufactured using these compositions are provided. A composition contains polyimide resin (A), phenol resin (B), and epoxy resin (C) components. The mixing ratio by weight (A)/[(B)+(C)] is 0.4 to 2.0, the ratio being the ratio of the weight of (A) to the total weight of (B) and (C). By using such a composition, multilayer bodies and circuit boards, excellent in dielectric characteristics, adhesiveness, processability, heat resistance, flowability, etc. can be manufactured. A composition contains a polyimide resin (A), a phosphazene (D), and a cyanate ester (E). D includes a phenolic hydroxyl group-containing phenoxyphosphazene (D-1) and/or a crosslinked phenoxyphosphazene (D-2) prepared by crosslinking (D-1), (D-2) having at least one phenolic hydroxyl group. By using such a composition, multilayer bodies and circuit boards with excellent properties can be manufactured.