The effective magnetic moment of Cr₂O₃ is determined by assuming that a proportional relation holds between its moment and the effective magnetic moment of hematite determined by the previous derived relaxation expression and the moments of Fe³⁺ ion and Cr³⁺ ion. The result obtained from the relation is found to be given by 0.10 in Bohr magneton which is in good agreement with the value obtained by use of the expression.