The present invention relates to a one-pot process for the production of poly carbodiimide cured polymers. comprising a reaction of (a) at least one polycarbodiimide with two or more carbodiimide functionalities per molecule. (b) at least one polyol with two or more hydroxyl functionalities per molecule, and (c) at least one cyclic carboxylic anhydride.

A curable resin composition containing: a curable resin; and a curing agent containing an imide oligomer, the imide oligomer containing an aliphatic diamine residue- and/or aliphatic triamine residue-containing imide oligomer that has, in a main chain, an imide skeleton and a substituted or unsubstituted aliphatic diamine residue having a carbon number of 4 or greater and/or a substituted or unsubstituted aliphatic triamine residue having a carbon number of 4 or greater, has a crosslinkable functional group at an end, and has a molecular weight of 5,000 or less. The curable resin composition is excellent in flexibility and processability before curing and excellent in adhesiveness, heat resistance, and dielectric characteristics after curing. An adhesive, an adhesive film, a circuit board, an interlayer insulating material, and a printed wiring board each produced using the curable resin composition are also provided.