In powder bed fusion (PBF), a type of metal-based additive manufacturing (AM) process, metal powders are deposited on a substrate and melted through selective laser-beam irradiation. Among AM processes, PBF yields excellent dimensional accuracy, and the built parts can be applied to molding dies and topology-optimized parts. Furthermore, PBF can be used to build porous structures. In this study, a highly functional die casting method was established using PBF, which involved a release agent supplied through the porous structure to the surface of the proposed die. The arrangement of the porous structure made it possible to apply the release agent to the deep groove, which is not possible using a spray as in conventional supply methods. The laser-irradiated area was visualized to confirm pore formation, and the building conditions of the porous structure suitable to supply the release agent were investigated. The resulting die casting characteristics were evaluated. Considering the obtained results, guidelines to build dies or molds for die casting with porous structures are recommended. The amount of release agent could be controlled at each position of the die casting die, and the melted Al alloy did not penetrate the porous structure. In addition, the obtained Al alloy casting did not exhibit any castability defects. Moreover, suitable control of the supply of the release agent enabled enhancement of the die casting characteristics.