Now, Guided Tissue Regeneration (GTR) membranes which used biodegradable polymer were used in dental clinics. However, these membranes did not have any biological function such as the promotion of cell adhesion. In this study, GTR membrane surface was hydrolyzed with alkaline solution and collagen or fibronectin which was cell-adhesive protein was immobilized on GTR membrane surface using water-soluble carbodiimide. Afterwards, the attachment and proliferation of human gingival fibroblasts was investigated. It revealed that collagen immobilization onto GTR membrane by alkaline hydrolysis for 10min enhanced cell attachment, but the degradation of GTR membrane was occurred. The development of another method for immobilization cell adhesive protein onto GTR membrane instead of alkaline hydrolysis was necessary.