A method and packaging machine for preparing rapidly disintegrating formulations for oral administration are disclosed. The present invention is characterized in that a powdery mixture including a pharmaceutically active ingredient and a sugar or a sugar alcohol powder is filled into a packaging material and, thereafter, the mixture, filled in the packaging material, is heated. The present invention can simply and economically prepare an oral formulation which undergoes rapid disintegration in the oral cavity and provides for high-quality administration to patients.