A radiation-sensitive composition containing a resist compound having a high sensitivity, a high resolution, a high etching resistance, and a low outgas which forms a resist pattern with a good shape is described. Further described is a method of forming a resist pattern using the radiation-sensitive composition. Still further described are a novel composition for forming a photoresist under coat film which is excellent in optical properties and etching resistance and contains substantially no sublimable substance and an under coat film formed by the composition. Still further described are a radiation-sensitive composition containing a solvent and a cyclic compound having a specific structure, for example, a cyclic compound (A) having a molecular weight of 700 to 5000 which is synthesized by the condensation reaction of a compound having 2 to 59 carbon atoms and 1 to 4 formyl groups (aldehyde compound (A1)) with a compound having 6 to 15 carbon atoms and 1 to 3 phenolic hydroxyl groups (phenol compound (A2)), and a cyclic compound for use in the radiation-sensitive composition.