The effects of Ta, Ti and Y addition substituting Zr in the Ni-Zr-Nb-Al metallic glass alloys have been investigated by using thermal analysis, X-ray diffractometry and transmission electron microscopy. Partial replacements of Zr with M(=Ta, Ti, Y) in Ni61Zr28Nb7Al4 alloy significantly enhance the glass forming ability and enlarge the undercooled liquid region during continuous heating of glassy ribbons. Fully glassy rods with the diameter of up to 2 mm can be fabricated by a copper mold casting method.