  We investigate a possibility of a composite Z' vector boson. For the
compositeness, the required gauge coupling g in low energy is not so big,
g^2/(4\pi) > 0.015 in the case of the U(1)_{B-L} model. We show that the
Stueckelberg model is effectively induced in low energy via the fermion loop
from the Nambu-Jona-Lasinio (NJL) model having the vectorial four-fermion
interaction. In terms of the renormalization group equations (RGE's), this
situation is expressed by the compositeness conditions. We find that the
solutions of the RGE's with the compositeness conditions are determined by the
infrared fixed points. As a result, the ratio of the masses of the extra
electroweak singlet scalar and the right-handed neutrino is fixed. The mass of
the composite Z' boson contains the contribution \Delta of the Stueckelberg
mass term. This nonzero \Delta might be a remnant of a strongly interacting
theory in high energy.
