If there is a clear clause in the agreement that it will take effect after being sealed, but only the legal representative signs it without an official seal, the agreement will not take effect for the time being. If there is no such clause that comes into effect after being sealed, the agreement will come into effect when both parties have the signatures of legal representatives and no official seals. The entry into force of the contract means that the established contract has certain legal binding force between the parties, which is usually called legal effect. The establishment and entry into force of a contract are often closely linked. The purpose of concluding a contract is to make the contract binding, so as to realize the rights and interests stipulated in the contract. If the contract fails to take effect, it will become a dead letter, and the parties will lose the purpose of concluding the contract. It is generally believed that the following conditions should be met: 1, and the contracting parties should be two or more parties; 2. There are two stages or processes of offer and acceptance stipulated by law; 3. Expression of intention to reach an agreement on the main terms (in some cases, some form is needed as the carrier of expression). In addition, for an actual contract, the actual deliverable should also be regarded as a requirement for establishment. If the above conditions are met, the contract can be established. As for the validity of the established contract, it depends on whether it is established according to law. As long as it is a legally established contract, it should be valid. Legal basis: Article 32 of People's Republic of China (PRC) Contract Law. If the parties conclude a contract in the form of a contract, the contract shall be established when both parties sign or seal it.