The present invention relates to an adhesion-preventing material comprising the following (1) and (2): (1) an A-B-A type or B-A-B type triblock copolymer that has an A segment containing poly(µ-caprolactone-co-glycolic acid) and a B segment containing polyethylene glycol； and (2) polyethylene glycol and/or methoxy-polyethylene glycol. The present invention provides an adhesion-preventing material that undergoes a sol-gel transition in response to temperature, that can be prepared before use more easily than before, that can be easily applied to invasion sites having a complicated shape or structure, that can exhibit an adhesion-preventing effect stably for a desired period of time, and that has excellent handling properties in laparoscopic surgery.
