The present article is a continuation of the authors works devoted to the theoretical study of the fine structure parameters, and other atom characteristics, for which there are no experimental data except for energies of levels of the fine structure. The authors have studied Zeeman structure of the 2p4f and 3p4f configurations and revealed its particular features — crossings and anticrossings of the magnetic sublevels. From splittings of levels in the assured linear range, the authors have calculated gyromagnetic ratios and compared them with their counterparts in the absence of the field. The study of the Zeeman structure is interesting in its own right. Furthermore, through Zeeman splitting in the linear domain of the magnetic field, one can determine the gyromagnetic ratios — one of the most important characteristics of the atoms. Calculation of the Zeeman structure is correct, if in the absence of the field, during the diagonalisation of the energy operator matrix, one obtains the calculated energies, pr