Whether the contract signed by the legal representative is invalid or not under the condition that the legal representative's ultra vires representative behavior is invalid is still to be determined, which deserves further clarification. The author believes that since the legal representative's ultra vires representative behavior is invalid and cannot bind the legal person he represents, then the legal person is not a party to the contract, and the contract is invalid from the beginning, which is of course affirmative and absolute to the legal person. Of course, according to the spirit of freedom of contract, the legal person where the legal representative is ultra vires can ratify the ultra vires behavior of the legal representative through legal internal decision-making procedures. Whether the signature of the chairman of your guarantee contract is valid, thus making the ultra vires representative behavior evolve into authorized representative behavior, and the contract signed ultra vires also becomes a valid contract binding on the legal person. However, without the "finishing touch" authorized by the legal person, the contract signed beyond the authority is still invalid.