  In this paper we consider the derivations for even part of the
finite-dimensional Hamiltonian superalgebra $H$ over a field of prime
characteristic. We first introduce an ideal $\frak{N}$ of $H_{\bar{0}}$ and
show that the derivation space from $H_{\bar{0}}$ into $W_{\bar{0}}$ can be
obtained by the derivation space from $\frak{N}$ into $W_{\bar{0}},$ the even
part of the generalized Witt superalgebra $W$. For further application we also
give the generating set of the ideal $\frak{N}$. Then we describe three series
of exceptional derivations from $ {H}_{\bar{0}}$ into $W_{\bar{0}}.$ Finally,
we determine all the derivations vanishing on the non-positive
$\mathbb{Z}$-graded part of $ H_{\bar{0}}$, the odd $\mathbb{Z}$-homogeneous
derivations, and negative $\mathbb{Z}$-homogeneous derivations from
${H}_{\bar{0}}$ into $W_{\bar{0}}.$
