The stability of cable-in-conduit superconductors has been experimentally investigated as a program of poloidal field coils for the Large Helical Device (LHD) project. On the excitation tests for the demonstration coil (TOKI-PF), we had found several problems on the stability of a cable-in-conduit conductor; strand movements, current distribution and current transition among the strands. Consequently, a new conductor was designed and fabricated focused on the stability. As a result of a zero-dimensional stability analysis, it was found that the conductor has high stability margin, 5x 10(5)J/m(3), at the design condition of 20.8 kA and 6.5 T. Current transfer performance after partial quenching has been investigated by a short sample test. In this paper, effects of the current transfer among the strands on the conductor stability will also be discussed.