A polymeric compound for photoresist of the present invention includes a monomer unit having 2,6-dioxabicyclo[3.3.0]octane skeleton in the structure. The monomer unit having 2,6-dioxabicyclo[3.3.0]octane skeleton includes a monomer unit represented by the following Formula (I): ##STR1##

wherein R is a hydrogen atom or a methyl group. The polymeric compound for photoresist may include a monomer unit having 2,6-dioxabicyclo[3.3.0]octane skeleton, a monomer unit having a group of adhesion to substrate, and a monomer unit having an acid-eliminating group. The polymeric compound for photoresist of the present invention exhibits not only adhesion to substrate, acid-eliminating property and resistance to dry-etching but also has well-balanced solubility in solvents for photoresist and alkali-soluble property.