A focal atrial tachycardia (FAT) with low inducibility can be challenging to treat with catheter ablation. A 17-year-old female had previously undergone an unsuccessful ablation due to low inducibility of the tachycardia. During the second session, an activation map with a few FAT was insufficient to identify the earliest activation site. However, by employing a novel pace mapping technique using dual chamber unipolar electrograms as a reference, we accurately identified the FAT origin and successfully performed the ablation. This technique may enable effective ablation with fewer radiofrequency applications in FAT where the earliest excitation site cannot be clearly identified.