The pandemic of Coronavirus or Covid - 19 has caused many entrepreneurs to be unable to carry on their economic activities temporarily. Some of them may have serious financial problems resulting in business closure. This situation brought legal issues in relation to the lease in the case that a lessor is still able to deliver the leased property, but a business owner, as tenant, is unable to carry on the business which is the main purpose of the lease within the lease period. In other words, it is the case that the purpose of the lease has been extinguished and the use of the leased property has become useless for the tenants. In such case, although the lessor is deemed to have performed his/her obligation by delivering the leased property, but if the tenant will have to pay the entire rent in all cases without exception, it may be unfair to the tenant. There are many legal principles that apply to these types of cases in foreign countries. In the countries with the common law system, there is a legal principle called Frustrationé, which allows parties to cite the reasons that their primary purpose of execution of a contract has been significantly extinguished after execution of the contract in order to be discharged from performance of obligation. The countries with the civil law system also have a similar concept of laws. For example, Germany, the Geschäftsgrundlageé has been developed with an idea that a change from the expectation of the underlying circumstances of the contract may lead to the termination of such contract. Most of the cases to which the above legal principles applied were disputes that arose during crisis such as war, which hinders everyday life and causes business disruptions, similar to the Covid - 19 situation. Both legal systems have two common bases. First, the parties may not raise only the difficulty of monetary payment as an excuse for non-performance. Second, in any situation that should be assumed to occur and which are risks that must be borne by either party, such as commercial risks or economic volatility, the party who bears such risk may not raise such situation as an excuse to be discharged from liability. For legal principles in Thailand, the author has analyzed the above issues under the Impossibility of Performance principle. In terms of the performance under subject of that obligation, it is unlikely to say that the performance in this case is impossible because the lessor is still in a position to deliver the leased property. Certain academicians are opinion that the true purpose of the obligation must also be taken into account. If the enforcement of performance is outside the scope of the primary purpose of the obligation to the extent that the receipt of debt payment will be useless to the creditor, it can be considered as a case where the performance becomes impossible as well. In addition, there have been some judgments of the Supreme Court that reflect such idea. According to law in foreign countries, academiciansû opinions, and the judgment of the Supreme Court in Thailand as mentioned above, the author considers that, to apply Impossibility of Performance principle to discharge tenants from their liabilities in a reasonable and fair manner, it must be the situation that the primary purpose of the lease has been extinguished to the extent that the use of the leased property becomes completely useless for the tenant. Moreover, the situation that affects the use of leased property must not be the generally commercial risk. Illustrative examples of the situation will be provided in this article.