The temperature dependence of the order parameter of the -CF3 group, S-CF3, at the chiral part in 4-[(1-trifluoromethylhepthyloxy)carbonyl]phenyl [(4’-octyloxy)biphenyl]-4-carboxylate (TFMHPOBC) has been investigated by NMR spectroscopy. The discontinuous change of S-CF3 was observed at the ferroelectric-antiferroelectric phase transition. This suggests the importance of the conformation around the chiral center for the appearance of the antiferroelectric phase.