Background: This study assessed whether the dissemination of public-access defibrillation (PAD) at the population level is associated with an increase in neurologically favorable outcomes among patients experiencing ventricular fibrillation (VF) in public vs. residential locations in Japan. Methods and Results: We enrolled adult patients with bystander-witnessed VF between 2013 and 2015. The primary outcome measure was 1-month neurologically favorable outcome defined by cerebral performance category 1 or 2. The number of survivors with neurologically favorable outcome attributed to PAD after VF arrest was estimated by location of arrest. A total of 16,252 adult patients with bystander-witnessed VF arrest were analyzed. In public locations, 29.3% (2,334/7,973) of out-of-hospital cardiac arrest (OHCA) patients received PAD, whereas 1.1% (89/8,279) of OHCA patients received PAD in residential locations. OHCA patients with PAD had significantly better neurological outcomes compared with those without PAD in public locations (51.8% vs. 25.5%, P<0.001), whereas there were no significant differences in neurologically favorable outcome between patients with or without PAD in residential locations (22.5% vs. 18.6%, P=0.357). The total number of patients with neurologically favorable outcomes attributed to PAD was estimated at 615 in public locations, but only 3 in residential locations. Conclusions: In Japan, when compared with residential locations, PAD works more successfully in public locations for adults with bystander-witnessed VF arrest.