  We discuss the production of the composite Higgs boson in topcolor models via
the gluon fusion process. We consider the contribution of color-octet massive
gauge bosons (colorons) strongly interacting with the top quark, in addition to
nonstandard contributions of the top-Yukawa coupling and heavy colored fermions
other than the top quark. In order to estimate the contribution of colorons, we
derive the low-energy effective theory by eliminating colorons by using the
equation of motion for colorons. We replace the composite operator (\bar{q}_L
t_R)(\bar{t}_R q_L) in the effective theory by the composite Higgs operator. We
then obtain the effective gluon-gluon-Higgs (ggH-) operator induced by colorons
and find that its coefficient (A_{col}) is proportional to m_{dyn}^2/M^2, where
M and m_{dyn} denote the coloron mass and the mass dynamically generated by
colorons, respectively. The contribution of colorons A_{col} becomes comparable
to the top-loop effect A_{top} for M=O(1TeV) and m_{dyn}=O(0.6TeV). Such a
large dynamical mass can be realized in top-seesaw (TSS) models consistently
with the experimental value of the top quark mass (m_t^{exp}), while the
dynamical mass itself is adjusted to m_t^{exp} in topcolor assisted technicolor
models (TC2). We find that the coloron contribution A_{col} can be sizable in a
certain class of TSS models: the contribution of colorons (the top-loop) is
dominant in the real (imaginary) part of the H->gg amplitude for the Higgs
boson mass m_H of the order of 1 TeV. On the other hand, enhancement of the
top-Yukawa coupling becomes important in TC2. We can observe signatures of the
Higgs boson in TC2 with m_H \sim 200 GeV even at the Tevatron Run II as well as
at the LHC. We estimate S/\sqrt{B}=3-6 for an integrated luminosity of 2
fb^{-1} and m_H=190 GeV at the Tevatron Run II.
