Article 245, Clause 1 of Civil Law regulates “if the person who takes possession of the real property tranquilly and futilely by the proprietary intent for 20 years register it, he would get the proprietary rights of it”. In 1993, the Constitutional Court said, the substantive interests about the real property of the object of a right between the owner of the real property who defaults exercising his rights for a long time and originally the unrightfully person who takes possession of the real property tranquilly and futilely by the proprietary intent for 20 years (it seems to be a constancy) shows the need of the acquisitive prescription system. Correlatively, under the fairness the possessor who has heavier substantial interest acquires the claim of transfer the real property from the owner of the real property. Therefore it does not violate the ideal and limit of guarantee of the property rights ruled by Article 23, Clause 1 of the Constitution. Additionally if the original owner forfeited of his ownership without an indemnification, compensation or restitution of unjust enrichment, it would be followed reflexive effect of the acquisitive prescription. It concretely formed the substance and limitation about gains and losses of the real property ownership which is the property rights ensured by the constitution. So it does not violate Article 37, Clause 1 of the Constitution which regulates limit of the restriction of the fundamental human rights. It should be comprehended the system of acquisitive prescription of real property is the system which is protecting the rightful person who gains rights substantially but cannot prove it. Namely, if the fact keeps on going for a long time, it would be easy to be disappeared the evidence of the relations of just rights so far. So the system of acquisitive prescription of real property makes the rightful person protect from that kinds of difficulty of proof. By the way, the current law is not clear. In case someone squats with malice or even the area of the dealing real property is over it of the register, current law has admitted the acquisitive prescription. It makes the rightful person sacrificed wrongfully. Under the property rights, it limited unfairly disposition rights that are about the personal usefulness and object of the property rights that is the core of substantial essence. Therefore Article 245, Clause 1 of Civil Law has the violation of the constitution because of essential violation of the private ownership of property. So it should be that only person who has possessed the real estate by the just right can get the acquisitive prescription.