Legal analysis: 1. Without the signature or seal of the employer, this contract is invalid. 2. If the unit only signs but doesn't seal or only seals and doesn't sign, as long as the legal representative of this unit performs his duties, that is, signs or seals on behalf of the unit, instead of signing a contract for his own affairs in his own name, then the contract is valid for the unit.

Legal basis: Civil Code of People's Republic of China (PRC).

Article 165 If the power of attorney is in written form, it shall specify the name of the agent, the matters to be represented, the authority and the time limit, and shall be signed or sealed by the principal.

Article 490 Where the parties conclude a contract in the form of a contract, the contract is formed when the parties sign, seal or fingerprint it. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it.