Primary progressive aphasia (PPA) is a progressive degenerative disorder that primarily affects language. Although the etiology of PPA has not been determined, autoimmune mechanism is known to be one possible pathophysiology. We investigate efficacy of steroid treatment in a patient diagnosed as both logopenic variant PPA and Sjögren's syndrome. After steroid treatment, her cognitive function, especially language ability showed improvement. And also, FDG-PET showed metabolic increase in the bilateral temporal lobe. However, on reassessment after stopping steroid treatment, her cognitive performance declined to pretreatment level.