  The $S=1/2$ ferromagnetic-antiferromagnetic bond-alternating spin chain with
the anisotropy on the ferromagnetic exchange interaction in magnetic field is
investigated using the numerical diagonalization and the density matrix
renormalization group analyses. It is found that the nematic-spin-dominant
Tomonaga-Luttinger liquid phase is induced by the external magnetic field for
sufficiently large anisotropy. The phase diagram with respect to the anisotropy
and the magnetization is presented.
