The purpose of this study was to evaluate root resorption and alveolar bone resorption pattern by jiggling movement. adult cats were divided into 4 groups (6, 12, 18, 24 days). ln test side, mesio-distal jiggling force was applied in right maxillary 1st premolar in 3 days cycle. ln control side, mesial force was applied in left maxillary 1st premolar, Radiographic and histologic observation were formed in 6, 12, 18, 24 days after force application. The results were as follow: Alveolar bone resorption was more severe by jiggling force than by unidirectional force. Root resorption pattern was not different between jiggling force and unidirectional force. Combined pattern of bone resorption and new bone formation appeared in jiggling group. New bone formation began to appear at periapical area of jiggling group after 24 days, because alveolar bone resorption was severe and extrusion resulted.