Legal analysis: If a contract signed by someone other than a legal person is authorized by the legal person, it will be valid. According to the above, the official seal of the unit is stamped, which means that the unit agrees to the contract, that is, the contract is valid. However, if there is any violation of laws and regulations in the contract, it will be invalid regardless of whether it is signed or not.

Legal basis: Article 465 of the "People's Republic of China and Civil Code" A contract established in accordance with the law shall be protected by law. A contract established in accordance with the law is only legally binding on the parties, unless otherwise provided by law.