  We study the big-bang nucleosynthesis (BBN) scenario with late-decaying
exotic particles with lifetime longer than $\sim 1$ sec. With a late-decaying
particle in the early universe, predictions of the standard BBN scenario can be
significantly altered. Therefore, we derive constraints on its primordial
abundance. We pay particular attention to hadronic decay modes of such
particles. We see that the non-thermal production process of D, ${\rm ^{3}He}$
and ${\rm ^6Li}$ provides a stringent upper bound on the primordial abundance
oflate-decaying particles with hadronic branching ratio.
