The present invention aims to provide a staple reinforcement for a surgical stapler that can be used in surgical staplers of various sizes, is easily passed through ports, and is less likely to shift during operation of the surgical stapler. Provided is a staple reinforcement for a surgical stapler, including a fabric layer containing a bioabsorbable material and a sponge layer containing a water-soluble polymer, the fabric layer and the sponge layer being integrally laminated.