  In this paper, we propose a discrete version of O'Hara's knot energy defined
on polygons embedded in the Euclid space. It is shown that values of the
discrete energy of polygons inscribing the curve which has bounded O'Hara's
energy converge to the value of O'Hara's energy of its curve. Also, it is
proved that the discrete energy converges to O'Hara's energy in the sense of
$\Gamma$-convergence. Since $\Gamma$-convergence relates to minimizers of a
functional and discrete functionals, we need to investigate the minimality of
the discrete energy.
