We report the experimental realization of the four-partite bound-entangled state, i.e., Smolin state  and demonstrate the superactivation of the bound entanglement. Bound entanglement is a class of multipartite entanglement that cannot be distilled into pure entanglement under local operations and classical communication (LOCC). Despite its undistillable property, this class of entanglement has interesting properties that are expected to be useful in quantum information processing (QIP). For instance, in the Smolin state, the bound entanglement can be activated into distillable entanglement when two of the parties get together. The process is called unlocking , and has been demonstrated experimentally . More importantly, the bound entanglement can be activated with the help of entanglement in other systems . The activation of bound entanglement, i.e., superactivation, plays an essential role in the QIP protocols using bound entangled states (e.g., remote information concentration ).