The use of a defibrillator with a monitor is recommended for the shock indication algorithm for in-hospital cardiac arrest; however, it is likely that many medical facilities are still equipped only with automated external defibrillators (AEDs). We experienced a case of dilated cardiomyopathy (DCM) complicated by pulseless ventricular tachycardia (pVT) in which an AED was used, but shock was deemed unnecessary after the first analysis. We believe that this case is suggestive of resuscitating cardiac arrest, for which defibrillation is indicated and reported here. A 65-year-old man who had DCM and diabetic nephropathy was admitted to our institution because of worsening heart failure. In the hospital, he suddenly had syncope and was diagnosed with cardiac arrest. Thereafter, cardiopulmonary resuscitation (CPR) was performed using an AED, and the monitor on the AED showed pVT. The first analysis of the AED announced unnecessary shock delivery. The pads of the AED were pressed firmly against the chest wall while continuous high-quality CPR was administered for two minutes. The second analysis of the AED revealed the necessity of providing shock for shockable rhythm. The patient experienced the return of spontaneous circulation after shock delivery. We were reminded that there are some clinical cases in which AED shock is not indicated for pVT and that even in such cases, it is important to continue high-quality CPR without panicking.