An object of the present invention is to provide an adhesion-preventing material which is capable of effectively preventing the surfaces of organs from adhesion, and which can be absorbed in the body with high safety and produced with ease and has high practical utility, as well as to a process for preventing adhesion by using the adhesion-preventing material.The present invention provides (1) an adhesion-preventing material comprising a crosslinked water absorbent poly-γ-glutamic acid as an effective ingredient; (2) the adhesion-preventing material described above, wherein the crosslinked water absorbent poly-γ-glutamic acid is in the form of powder having a water absorption coefficient in the range of 800-2000; (3) a process for preventing organ from adhesion, comprising a step of bringing the adhesion-preventing material described above into contact with the surface of a local organ; and (4) the process for preventing adhesion described above, wherein the surface of the local organ is in wet state.