摘要： 《合同法》第45条第1款承认当事人享有对合同效力约定附条件的自由。条件具有意定性、未来性、或然性和合法性的特征。生效条件与解除条件是我国实证法规定的条件类型。附生效条件的合同，自条件成就时生效；附解除条件的合同，自条件成就时失效。为维护公益或私益计，亲属法上非财产性的法律行为、票据行为、不动产让与合意等法律行为，不得附加条件。在未决期间，当事人应当诚信行事，以尊重相对人的期待权。《合同法》第45条第2款基于诚实信用原则，确立了条件成否的拟制规则，但此规定稍显僵化。依实证法规定，条件成就不具有溯及力，但该规则属任意规范。

关键词: 生效条件, 解除条件, 未决期间, 拟制

Abstract: The first paragraph of Article 45 of Contract Law provides that the parties have the freedom to agree to attach conditions on the validity of the contract. Conditions are characterized by intentionality, futurity, probability and legality. Conditions on the entry into effect and conditions on dissolution are two types of conditions stipulated by positive law in our country. A contract with collateral conditions on its entry into effect shall become effective upon the fulfillment of the conditions. A contract with collateral conditions on its dissolution shall lose its validity upon the fulfillment of the conditions. However, for the protection of public welfare or private benefits, the family law on non-property legal acts, bill behavior, consensus on transfer of real estate and other legal acts shall not be conditional. During the pending period, the parties shall act in good faith in order to respect the expectant right of the relative person. Based on the principle of honesty and good faith, the second paragraph of Article 45 of Contract Law establishes the fictitious rules on conditional achievement or non achievement; however, this provision is slightly rigid. In accordance with the provisions of positive law, the achievement of conditions has no retroactive effect; the provision is arbitrary norm.

Key words: Conditions on the Entry into Effect, Conditions on Dissolution, Pending Period, Fictitious Rules