1. Whether a contract signed by someone other than myself is valid depends on different situations, as follows:

(1) is valid only with my authorization or permission;

(2) Without my consent, it is generally invalid, unless it constitutes an agency by estoppel or with my consent or ratification.

2. Legal basis: Article 490th of the Civil Code of People's Republic of China (PRC).

If the parties enter into a contract in the form of a contract, the contract shall be established when the parties sign, seal or press their fingerprints. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it. A contract shall be concluded in written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.

Second, which contracts are valid?

A contract that meets the following conditions is valid:

1, the parties to the contract have corresponding civil capacity;

2. The intention of the parties to the contract is true;

3. The contract does not violate the mandatory provisions of laws and administrative regulations, and does not violate public order and good customs.

3. Which contracts are invalid?

Invalid contracts include:

1, the intention of the contract is false, and the illegal purpose is covered up in a legal form;

2, the parties maliciously collude to harm the legitimate interests of others to sign a contract;

3. The contract violates the mandatory provisions of laws and regulations;

This contract violates public order and good customs.