We report the case of a middle-aged woman with Cotard's syndrome in whom clinical course was evaluated according to stages. Longitudinally this syndrome seems to have three stages, namely germination, blooming and chronic (depressive type/paranoid type) stages. In this patient, the chronic stage, primarily characterized by delusions, was observed without raising suspicion of affective disorder. She did not respond to any pharmacotherapies, but improved dramatically after ECT performed during the chronic stage. Although symptoms change according to the stage, most cases of Cotard's syndrome may belong to the affective spectrum and are probably best treated with ECT, as documented here. In evaluation of the mode of separation between emotion and cognition during follow-up it is important to consider stage and diagnosis.