PROBLEM TO BE SOLVED: To provide a surface structure body for protein adsorption inhibition, capable of inhibiting protein adsorption without using a chemical liquid.SOLUTION: A surface structure body for protein adsorption inhibition comprises a fine rugged structure body having fine projection groups with a plurality of fine projections arranged at least on one surface of a base material. In the fine projections, a cross-sectional area of a horizontal section gradually decreases from a root to a crown of a projection, and the crown has a curved surface, and a distance between the neighboring fine projections is 50-500 nm in average.