  We study the possibility to apply phenomenological approach to the
description of magnetic transitions in UGe$_2$ at ambient pressure with the
help of Landau free energy expanded to 8th order in magnetisation. The analysis
shows that for certain values of parameters in front of M4, and M6 terms in the
free energy there is possibility for the appearance of two successive phase
transitions between the low-magnetisation and high-magnetisation phases with
the same magnetic structure. We establish the relation of the parameters in
Landau energy, for which the phase transition from the disordered to
low-magnetisation phase is of second order as the experimental data shows. We
have also found the relations between the Landau coefficients which result in
transition of crossover type between the low- and high-magnetisation phases
when temperature is lowered.
