Catecholaminergic polymorphic ventricular tachycardia (CPVT), one of the inherited fatal arrhythmic syndromes, is usually diagnosed as bi-directional ventricular tachycardia during exercise. CPVT often causes faintness and/or cardiac arrest in younger adults resulting in a poor prognosis, with 60％ ten-year survival. Although 50–60％ of CPVT is caused by the mutation in the cardiac ryanodine receptor gene (RYR2), most are sporadic and familial cases are rare. Here we report familial CPVT cases of a 34-year-old woman (proband) and her two sisters. All of them had been implanted with a cardioverter defibrillator (ICD) due to syncope or resuscitated after ventricular fibrillation (VF). Additionally, five of her family members died in their thirties. The genetic study identified a novel pathogenic variant, F4087L, in the RYR2 gene in the proband, her sisters, and proband’s son and niece. Even after ICD implantation, defibrillator shocks were needed to cope with VF in the proband and her sisters. However, additional pharmacological therapies such as beta-blockers, flecainide, and Ca channel blockers could suppress the recurrence of syncope or VF in all patients. These findings suggest that early clinical and genetic diagnosis for CPVT may provide appropriate pharmacological and non-pharmacological therapies to patients and their asymptomatic family members, including infants, for primary prevention of sudden death.