  The recent data from H1 Collaboration on hadron multiplicity in diffractive
DIS has been studied in the framework of perturbative QCD as a function of
invariant diffractive mass. The formulas obtained explain the observed excess
of particle production in diffractive DIS relative to that in DIS and $e^+e^-$
annihilation. It is shown that the results are sensitive to the quark--gluon
structure of the Pomeron. Namely, the data say in favour of a super-hard gluon
distribution at the initial scale.
