Results are presented from theoretical investigations of Rydberg matter of magnesium by the Hartree-Fock method with allowance for the width of the atomic levels. It is shown that, Rydberg matter of Mg₂ can be formed at any intensity of excitations in the optical energy range. Thus, the intensity there is less, the lifetime and the potential hole for a condensate of excitations are more. The most stable excitations in Mg₂ are found out at the distance between atoms about 9 Bohr radiuses.