The Sc3+ ion migration in the scandium tungstate solid was qualitatively demonstrated. For clarifying the exact migrant quantitatively, modified Tubandt electrolysis was performed for the Sc-2(WO4)(3) solid. As a result of the strict compensation, that is, vaporization and adherence compensations, a weight increase at the cathodic side and a weight decrease at the anodic side were reproducibly observed after the electrolysis. In addition, the Sc concentration at the cathodic side was increased and a corresponding decrease at the anodic side was observed. Therefore, the Sc3+ ion conduction in the Sc-2(WO4)(3) solid was quantitatively demonstrated.