Transformation behaviour of thermo-mechanically treated Ti-Ni-Cu ternary alloys have been investigated by means of electrical resistivity measurements and X-ray diffraction. The obtained results are as follows. (1) The B2→B19´ transformation start temperature in Ti-Ni-Cu ternary alloy does not almost change with increasing Cu-content from 1at% to 5at%. (2) The B2→B19´ transformation start temperature increases by applying thermo-mechanical treatments to the solution treated alloys in Ti-Ni-Cu ternary alloys whose Cu-content is 2at%. (3) Cu addition to the Ti-Ni binary alloy depresses the R phase transformation