Effect of temperature and magnetic field on the structure and magnetic properties of Fe$_{50.1}$Mn$_{22.7}$Ga$_{27.2}$ і Fe$_{51.6}$Mn$_{17.8}$Ga$_{30.6}$ alloys is investigated in a temperature range 100 К < T < 580 К by using elastic neutron diffraction (ND) and magnetometry. The degree of atomic order as well as magnetic moments localized at the Mn and Fe sites in the investigated Fe$_{2}$MnGa alloys are experimentally evaluated using the ND data. Some disagreement between the experimental and calculated values of magnetic moments localized at the Mn and Fe sites can be explained by noticeable atomic disorder in the prepared Fe$_{2}$MnGa alloys. If antiferromagnetic order really exists in $L1_{2}$-phase containing Fe$_{50.1}$Mn$_{22.7}$Ga$_{27.2}$ alloy, this order has not a collinear character.