Including with the cellulose derivative, the said cellulose derivative and the phosphatide which consist of the repetition unit which is displayed with the below-mentioned formula the composition which becomes, including those production methods, and the said derivative or the said composition, the adhesion prevention material which becomes. R1, R2, R3 H, ch2 cooh, is ch2 coox, or ch2co phosphatidyl ethanolamine, X is total of degree of substitution of alkaline metal or alkaline earths metal, ch2 cooh and ch2 coox 0.3 - 2.0, degree of substitution of ch2co phosphatidyl ethanolamine is 0.001 - 0.05.下記式で表される繰り返し単位からなるセルロース誘導体、該セルロース誘導体とリン脂質とを含んでなる組成物、それらの製造方法、ならびに該誘導体もしくは該組成物を含んでなる癒着防止材。R1、R2、R3は-H、-CH2-COOH、-CH2-COOX、または-CH2CO-ホスファチジルエタノールアミンであり、Xはアルカリ金属またはアルカリ土類金属、-CH2-COOHと-CH2-COOXの置換度の合計が0.3~2.0であり、-CH2CO-ホスファチジルエタノールアミンの置換度が0.001~0.05である。
