Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disease characterized by dilatation and akinesis of the right ventricle, and causes life-threatening ventricular arrhythmia. Mutations of plakophilin-2 (PKP2) have recently been identified as one causative abnormality in ARVC. A case of ARVC with a mutation of PKP2 is reported here. Direct sequencing of the patient's DNA revealed an insertion mutation in exon 8 of PKP2 (1728_1729insGATG). The mutation caused the frameshift and the premature termination of translation (R577DfsX5). This is the first case report of PKP2 mutation found in Japanese ARVC patients.