Sheet binding apparatus using concave-convex members and image forming apparatus having same
A sheet binding apparatus which forms concavity and the convexity on a sheet bundle including a plurality of sheets in a thickness direction so as to bind the sheet bundle, the sheet binding apparatus includes: a pair of concave-convex members, each of which has concave-convex portion in the thickness direction of the sheet bundle and which forms the concavity and the convexity on the sheet bundle in the thickness direction while niping the sheet bundle therebetween; wherein in the pair of concave-convex members, one of the concave-convex members has a greater difference in height of the concave-convex portion than that of the other concave-convex member which engages with the above-described concave-convex member.