We have investigated the physical properties of a pyrochlore hafnate using ac magnetic susceptibility , dc magnetic susceptibility , isothermal magnetization , and heat capacity measurements, and determined the magnetic ground state by neutron powder diffraction. An upturn is observed below 6 K in , however both and do not show any clear anomaly down to 2 K. The shows a well-pronounced anomaly indicating an antiferromagnetic transition at K. The long-range antiferromagnetic ordering is confirmed by neutron diffraction. The refinement of the neutron diffraction pattern reveals an all-in/all-out antiferromagnetic structure, where for successive tetrahedra the four magnetic moments point alternatively all-into or all-out-of the tetrahedron, with an ordering wave vector k = (0, 0, 0) and an ordered state magnetic moment of /Nd at 0.1 K. The ordered moment is strongly reduced, reflecting strong quantum fluctuations in ordered state.