This study aimed to clarify the effects of vertical bone defect width and a ferrule on fracture of the fragments of fractured tooth reattached with adhesive resin cement (reattached tooth). The reattached tooth was built up by a fiber post and composite resin core for abutment and formed to the abutment with or without a ferrule. The vertical bone defect was fabricated with a V-shaped defect in different widths. The fracture load was evaluated using a universal testing machine. The vertical bone defect did not affect the fracture load, but a ferrule increased the root fracture load. For the specimens without a ferrule, debonding between the composite resin core and the root at the coronal loading side and fractures at the apical side of the root were found. In conclusion, the ferrule at abutment could affect fracture load and modes, and the bone defect width did not.