  The consistency relation between non-linear parameters $f_{NL}$ and
$\tau_{NL}$ characterizing Non-Gaussianity generated during the inflationary
period have been emerged as a useful tool which have a possibility to rule out
a large class of inflationary models all at once. In our previous work, we
extended the Suyama-Yamaguchi inequality up to 1-loop corrections. In this
paper, we derive an inequality extended up to {\it all} loop corrections which
has the same expression with the original Suyama-Yamaguchi inequality,
$\tau_{NL} \geq (6/5f_{NL})^2$, where the equality is not satisfied in the case
of single field models any more.
