We optimize the atomic structures of icosahedral Ni6Zr5Nb3 with an added H-atom in a periodic cell as a local structural model of NiZrNbH amorphous alloys by the rst principles calculation, and identify energetically favorable H-atom sites in the local structure of the amorphous alloys. We nd that a H-atom is favorably located not at tetrahedral sites in the icosahedral cluster but at octahedral sites in the region of inter-cluster. We also nd that a H-atom in some tetrahedral sites induces a rearrangement of the local structure from icosahedral to fcc-like, which seems to correspond to a local crystallization in the amorphous phase. These results give a fundamental behavior of hydrogen atoms in NiZrNb amorphous alloys and information to elucidate the mechanism of the electrical transport in the NiZrNb amorphous alloys with H-atoms.