Traumatic root fracture involves dentin, cementum, and pulp. It occurs in 0.5% to 7.0% of all trauma cases in permanent teeth. Diagnosis of horizontal root fracture is critical for its management. However, there are many considerations to the diagnosis of horizontal root fracture. Continuous clinical and radiographic examinations are positively necessary. This case report describes delayed diagnosis of horizontal root fracture of upper right central incisor by continuous clinical and radiographic examinations.