  The dynamics of the glueballs is important in the context of the experimental
search as well as for understanding the non-Abelian gauge theory. The glueballs
of the dark $SU(N_c)$ Yang-Mills theory are also good candidates of dark
matter. In this proceedings contribution, we report on the result of the
lattice calculation of the interglueball potential of the Yang-Mills theory
with the color numbers $N_c=2,3,4$, with a detailed inspection of the
systematics due to the discretization.
