Legal analysis: the handwritten pledge and the agreement signed by the two parties **** the same, in principle, is legally effective. Whether or not to notarize, belongs to the parties to the free choice of the scope of power. However, if the guarantee or agreement with the following legal provisions of the situation, is invalid.
Legal basis: the Chinese people's *** and National Code
Article 502 A contract established by law shall take effect from the time of its formation, except as otherwise provided by law or agreed by the parties. Where a contract is subject to ratification or other formalities in accordance with the provisions of laws or administrative regulations, such provisions shall apply. If the failure to apply for approval or other formalities affects the entry into force of the contract, it does not affect the validity of the provisions of the contract on the fulfillment of the obligation to apply for approval or other relevant provisions. If the party that should have gone through the formalities of applying for approval, etc., fails to fulfill its obligations, the other party may request it to bear the responsibility of violating such obligations. In accordance with the provisions of laws and administrative regulations, the provisions of the preceding paragraph shall apply to the change, transfer and dissolution of the contract, where such procedures should be applied for approval.
Article 506 The following exemption clauses in a contract shall be invalid: (1) causing personal injury to the other party; (2) causing property damage to the other party due to intent or gross negligence. The contract shall be invalid if one of the following circumstances exists: (1) one party concludes the contract by means of fraud or duress to the detriment of the state interests; (2) malicious collusion to the detriment of the state, the collective or the interests of a third party; (3) concealment of an illegal purpose in a legal form; (4) detriment to the interests of the social public ****; (5) violation of the mandatory provisions of the laws and administrative regulations.