Self-healing of damage in materials is most desirable to improve the reliability of materials. In heat resisting steels, creep cavities lead to the premature and low ductility fracture, and long time creep rupture life and ductility chiefly depend upon the behavior of creep cavity growth. If the growth of creep cavities could be suppressed, creep rupture life and ductility should be improved remarkably. It was thought that precipitation of a stable compound at creep cavity surface suppresses the creep cavity growth and improves creep rupture properties. New heat resisting steels were laboratory-melted in order to verify the self-healing effects by the precipitation of the compound. Preliminary results showed that the precipitation of a stable compound at creep cavity surface is very useful method to improve creep rupture properties.