Legal analysis: Valid. As a document of creditor's rights, an IOU is valid even if it has only the signature of the debtor and no signature or seal of the creditor, as long as the creditor and the fact of the debt can be identified. An IOU does not necessarily require the signatures or seals of both the creditor and the debtor to be valid. The key to the validity of the IOU lies in whether it can prove the fact that the debt is owed. Even if the IOU has formal flaws, the existence of the debt can be determined through a comprehensive analysis of relevant facts.

Legal basis: "Regulations of the Supreme People's Court on Several Issues Concerning the Application of Law in the Trial of Private Lending Cases" Article 2 When a lender files a lawsuit with the People's Court, it shall provide IOUs, receipts, IOUs and other evidence of creditor's rights and other evidence that can Evidence proving the existence of a legal relationship between lending and borrowing. If the creditor's rights certificates such as IOUs, receipts, and IOUs held by the parties do not indicate the creditor, and the party holding the creditor's rights certificates files a private loan lawsuit, the People's Court shall accept it. The defendant raised a fact-based defense against the plaintiff's creditor qualifications. After trial, the People's Court held that the plaintiff did not have creditor qualifications and ruled to dismiss the lawsuit.