Adhesion between swollen hydrogels was studied using a simple tack-evaluation technique by a point contact in air at room temperature. The hydrogel used here was poly(sodium acrylate) (PSA) gel physically cross-linked by aluminum ions. The adhesion force and the separation energy showed a power-law increase with separation velocity, normal force, and waiting period prior to separate. Effects of the degrees of protonation in PSA as well as of dehydration on the adhesive properties are also presented. The results are discussed in terms of the surface molecular interaction and the bulk elastic and viscous properties.