Problem To provide an orthodontic appliance that by ensuring proper occlusal position of teeth in an oral cavity enables teeth straightening to thereby achieve precise correction ensuring proper occlusion, and enables performance of teeth straightening by residing in the oral cavity for a certain time period such as during sleep. Means for Solving the Problem A configuration comprising an orthodontic unit to be removably fitted in the oral cavity and molar caps erected near the orthodontic device, wherein the orthodontic unit comprises a pair of U-shaped devices formed of a maxillary orthodontic unit and a mandibular orthodontic unit united by wires, teeth are straightened while positions of upper and lower jaws are being adjusted, the molar caps comprise large covering lids for anchoring that are slightly higher than surrounding teeth, and the orthodontic unit is mounted on outer peripheries of the molar caps by locking to the molar caps through grooves provided in the maxillary orthodontic unit of the orthodontic unit.
