  The explicit form of the Griffiths singularity in the random ferromagnetic
Ising model in external magnetic field is derived. In terms of the continuous
random temperature Ginzburg-Landau Hamiltonian it is shown that in the
paramagnetic phase away from the critical point the free energy as the function
of the external magnetic field h in the limit h -> 0 has the essential
singularity of the form $\exp[-(const)h^{-D/3}]$ (where 1<D<4 is the space
dimensionality). It is demonstrated that in terms of the replica formalism this
contribution to the free energy comes due to off-perturbative replica instanton
excitations.
