An ultrashort laser pulse (ULP) excites the spin precession in the magnetically-ordered dielectrics, as stated in [1-3]. The spin-reorientation phase transition in orthoferrites can be induced by an ULP and the rise of time of this transition is equal to a few picoseconds [1, 2]. The Landau–Lifshits equation-based description of the reorientation phase transitions dynamics was considered in [4–7]. The generalized coordinate  2sin expansion was used for the free energy representation: 4 2 2 10 sin sin)( K TKFF (1). The summand, which is proportional to the value of H(t)MsinΨ and corresponds to the interreaction with the field, enters the F0 term. The parameter  is the angle between the magnetization vector and the anisotropy axis and the external field H(t). In the elementary case, the direction of the H(t) vector coincides with the axis of all anisotropies; the coefficients K1(T) and K2 are the scalar parameters of these anisotropies, whose changing initiates the onset of reorientation phase transitions.     Let us consider the following expansion of the free energy:  4 20 2 10 cos )(cos)( K TKFF (2). The free energy representation is due to the fact that the anisotropy axes would be probably nonparallel one another in the general case. The equilibrium magnetization orientation X = cos is determined by the expression: 002 2 sin 2 02cos4 224302cos484402cos16 5 8 6 02cos162168216 pXp XpXpgpXgp XgpXgpgXg   (3), where p = MH/ K1 and g = K2/ K1.   We derived the hysteresis dependence of the value X on the external parameter p from expression (3). This hysteresis determines the region for optical bistability observation in the opto-magnetic inverse Faraday effect. This effect may be recorded in the “pump-probe” geometry. The pump is the effective magnetic field of the high-power exciting ULP and the probe is the magnetic polarization of the weak ULP, which is transmitted through the excitation area.