  In this paper a model for $3d$-subsystem of transition $3d$-metals has been
proposed and used for calculation of the cohesive energy dependent on $3d$-band
filling of particular metal, its bandwidth and effective intra-atomic
interaction value. It has been shown that the model enables one to explain the
observed peculiarities of cohesive energy effect on the atomic number. The
nature of two parabolic dependencies of cohesive energy on $3d$-band filling
has been clarified. The calculated values of cohesive energy are close to those
experimentally obtained for Sc-Ti-V-Cr-Mn-Fe series.
