Background We hypothesized that the dominant driver exists for maintaining atrial fibrillation (AF) in human. The objectives of this study were to explore the spatiotemporal change of this dominant driver and its clinical significances. Methods and Results We performed non-contact mapping (NCM) and analyzed virtual electrograms during AF in 24 patients (male 22, 50.0짹12.7 years old; 16 paroxysmal AF (PAF), 8 persistent AF (PeAF)) undergoing catheter ablation. The activation patterns of spontaneous or induced AF were mapped for three minutes (3 episodes, each 1 minute). The location and serial change of dominant frequency (DF) were analyzed by Fast Fourier transform. Results: 1. DF existed at the left atrial appendage (LAA)-left pulmonary vein (LPV) junction (45.8%), LAA (20.8%), LA roof (16.7%), right pulmonary vein (RPV) trunk (12.5%), and LPV trunk (4.2%). There was no significant spatial change of DF during each 1-minute period, and DF locations of PAF were not significantly different from those of PeAF. 2. There was no significant difference in the temporal change in DF and DF value between PAF and PeAF (1st minute 5.5짹1.5 Hz vs. 5.2짹1.1 Hz; 2nd minute 5.5짹1.6 Hz vs. 4.8짹1.5 Hz; 3rd minute 5.6짹1.6 Hz vs. 4.5짹2.0 Hz, p=NS). 3. During 15.1짹9.4 months of follow-up, DF was more commonly found at the LAA-LPV junction in whom AF recurred (75%) compared with those without recurrence (31.3%, p=0.03). Conclusion DF of human AF mainly exists at the LAA-LPV junction, LAA, and LA roof. LAA-LPV junction is the common DF site in patients with recurrent AF after catheter ablation, suggesting the possibility that anisotropic structure such as ligament of Marshall or LAA ridge associate with higher recurrence after initial successful ablation.