High pressure and high magnetic field experiments have been performed on the ferrimagnetic Er₆Fe₂₃ compound. The erbium-iron interaction parameter is found to be independent of pressure, magnetic field and temperature in the range of the experimental facilities (p<or=5 kbar, mu ₀H<or=35 T and 4.2<or=T<or=300K). The relative volume dependence of the iron moment in Er₆Fe₂₃ at 4.2K is almost equal to the value in pure iron.