A disease treatment drug having high pharmacological effects and no side effects is provided, the disease treatment drug being capable of intensively delivering an iron or manganese porphyrin complex capable of removing active oxygen to abnormal tissue within a living body, and effectively removing the active oxygen within the abnormal tissue. The disease treatment drug contains an iron or manganese porphyrin complex nanocapsule housing an iron or manganese porphyrin complex within a nanosized capsule. In the disease treatment drug, disease of abnormal tissue having a high concentration of active oxygen can be treated by the iron or manganese porphyrin complex delivered into the abnormal tissue as a result of the nanocapsule, without affecting normal tissue having a low concentration of active oxygen, and side effects can be suppressed.
