To provide a photoresist polymer compound for liquid immersion exposure which can form a resist film having excellent water resistance, a photoresist resin composition for liquid immersion exposure, a photoresist resin composition for liquid immersion exposure which can clearly and accurately form a fine pattern, and a method for producing a semiconductor.

The photoresist polymer compound for liquid immersion comprises 0.1-10%, in the molar ratio, of at least one monomer unit having a 5-20C alicyclic skeleton, which contains 6-15 atoms bonded in a straight-chain form from the carbon atom of the main chain of the polymer, and may contain a fluorine atom at the terminal atom of the straight-chain atom.