we investigated the interaction of hORC1 413-511  with various DNAs derived from human c-myc promoter and telomere region, having G4 structures. wtPu22 and wtPu19 were identified previously as nuclease hypersensitive element III 1  (NHE III 1 ) of the human c-myc promoter region. wtPu22 and wtPu19 were revealed to dominantly fold into a parallel-type G4 structure. Their mutants, mtPu22 and mtPu19, were revealed to fold only into a parallel-type G4 structure. TeloDNA was derived from a sequence of the human telomere region, (TTAGGG) n . G4 structures formed from a telomeric sequence have been well-studied and the NMR structure of teloDNA was reported to be the (3+1)-type G4 structure. In this study, we showed the binding affinity to G4 relative to dsDNAs using fluorescence anisotropy (FA). Then, we demonstrated the conformational changes of hORC1 413–511  and G4-DNA in response to their binding by circular dichroism (CD) and NMR. Moreover, the binding sites for that interaction had been identified.