A positive type resist composition for forming a high resolution resist pattern and a method of forming a resist pattern are provided which use a low-molecular-weight material as a base component, and a compound and a dissolution inhibitor that are each suitable for the positive type resist composition. Here, the compound is a non-polymer having a molecular weight of 500 to 3000, and is decomposed under the action of an acid to produce two or more molecules of a decomposition product having a molecular weight of 200 or more; the dissolution inhibitor comprises the compound; the positive type resist composition comprises the compound and the acid generator component; and the method of forming a resist pattern uses the positive type resist composition.