  Let $\mathcal{R}$ be a commutative ring with identity, $I(X,\mathcal{R})$ be
the incidence algebra of a locally finite pre-ordered set $X$. In this note, we
characterise the derivations of $I(X,\mathcal{R})$ and prove that every Jordan
derivation of $I(X,\mathcal{R})$ is a derivation provided that $\mathcal{R}$ is
$2$-torsion free.
