Although late complete atrioventricular block (CAVB) is especially rare as periprocedural complication of atrioventricular nodal re-entrant tachycardia treatment, this complication can necessitate permanent pacemaker implantation. The present case is that this late CAVB can be caused only during periprocedural period by the indirect or functional effects on the fast pathway of AV node because this case has paroxysmal supra-ventricular tachycardia with pre-existing PR prolongation, and the PR prolongation improved within normal PR interval after curing of the late CAVB. Further, when the late CAVB occurs within a few weeks after ablation, such bradyarrhythmia as periprocedural complication may be reversible and indication of a permanent pacemaker implantation should be carefully considered.