The sale contract of unmovables such as lands or building is a bilateral contract in Korea. The seller must transfer the title of the movables to the buyer at the same time as the buyer pays the purchase price. In cases where the seller and the buyer`s obligation should be simultaneously performed, in order for the seller to cancel the contract, the seller has to give a notice of the acceptance of the tender to the buyer, tendering his or her own performance, or preparing for the tender of performance of his or her obligation. However, contracting parties often promise that the contract will be automatically cancelled, without the notice or the manifestation of intention of the cancellation, once the buyer does not pay the purchase price at the due date of payment. In this case, though, according to Korean Supreme Court`s decisions, in order for the sale contract to be canceled, the seller should tender his or her performance as long as the seller and buyer`s obligation should be simultaneously performed. However, if there are special circumstances on the part of the buyer to give up the right, the seller does not have to tender his or her performance. In addition, after tendering the performance of his or her obligation, the seller can give the buyer the notice that ther will be automatically cancelled if the buyer do not pay the price within the specified period of time. Accordingly, without the special circumstances aforementioned, in order for the buyer to allege the cancellation of the contract, the seller`s full performance is required. In a land sale contract, the seller should tender all documents that are essential for transferring the title of the land such as title certificate, certification of official registration of a seal, and officially registered seal, etc. Recently, however, the Supreme Court held that the seller did not have to tender all documents that need for the buyer to transfer the title, where the buyer delayed his or her obligation. With the Korean Supreme Court` 2012Da65867 Decision, this article analyses the effect of automatic rescission made by the seller and the buyer, and futhermore exercises what kinds of documents the seller has to tender where the buyer delay his or her performance.