This study reports hydrogen absorption property of newly-synthesized RAP (rubeanic-acid polymer)-protected palladium nanoparticle (RAP-Pd). From powder X-ray diffraction measurements, the lattice constant of Pd nanoparticle was revealed to increase by 0.11 angstrom under 600 Torr hydrogen gas condition at room temperature, indicating that the hydrogen absorption occurs in the Pd nanoparticle. Solid-state H-2-NMR spectrum under deuterium gas showed that three different components exist in RAP-Pd, which are derived from imino group, terminal amino group in the RAP and absorbed deuterium atom inside the Pd nanoparticle. This result gives an expectation of the hydrogen absorption in RAP itself.