Provided is an adhesion preventing material having operability that can be reliably attached to a living tissue and in which tissue adhesion and biodegradability are improved. A water-soluble support layer having a thickness of 1 to 1000 μm containing a water-soluble polymer, and an anti-adhesion layer having a thickness of 1 to 1000 μm containing a biodegradable polymer； It has a structure in which a branched polyalkylene glycol having 3 to 8 terminal hydroxyl groups per molecule and a polyhydroxyalkanoic acid are bonded, and the mass ratio of the branched polyalkylene glycol to the total mass is 1 to 30%. There is an adhesion prevention material.生体組織に確実に貼り付けできる操作性を備え、かつ組織密着性及び生分解性が改善された癒着防止材を提供すること。 水溶性ポリマーを含む、厚さが１～１０００μｍの水溶性支持層と、生分解性ポリマーを含む、厚さが１～１０００μｍの癒着防止層と、を有し、上記生分解性ポリマーは、一分子あたり３～８個の末端ヒドロキシル基を有する分岐型ポリアルキレングリコールとポリヒドロキシアルカン酸とが結合した構造を有し、かつ全質量に対する上記分岐型ポリアルキレングリコールの質量比率が１～３０％である、癒着防止材。
