民法第406條規定：「所謂贈與，係當事人約定，一方以自己之財產無償給與他方，他方允受之契約。」而依第408條第一項之規定，在贈與物之權利移轉前，贈與人得任意撤銷其贈與。就此觀之，若在當事人成立金錢之贈與契約後，贈與人據此簽發支票交予受贈人收執，贈與人是否仍得撤銷贈與？若受贈人向贈與人行使票據上之追索權，贈與人得否以贈與契約已撤銷，拒絕付款？爲解答上述問題，本文援用法律經濟分析觀點，嘗試對於贈與契約與其他交易契約作更精確的區分。本文認爲，當契約應否定性爲贈與契約有所爭議時，吾人應著眼於當事人間之關係。此外，雖然字據的訂立無法發揮有效率的的信號功能，以將信守承諾的贈與人與偽裝者加以區別，因此吾人不能以字據之訂立作爲決定悔約權是否被剝奪的標準。但支票的交付則應另當別論。本文希望藉由經濟分析觀點的引介與運用，吾人對於悔約權的理論與實務，將會有更清楚的了解。

Article 406 of Civil Law: "A gift is a contract whereby the parties agree that one of the parties delivers his property gratuitously to another party and the latter agrees to accept it." According to Article 408, so long as the right of the gift has not been transferred to the donee, the donor can revoke the gift. So, can the donor revoke the gratuitous promise if she writes a bank check to the donee after the gift contract was made? Can the doner refuse to pay when the donee exercise the recourse right of the bank check? To solve questions mentioned above, this paper, employing the approach of law and economics, tries to differentiate gift contract from market exchange. It suggests we can look to the relationship between donor and donee when it is difficult to ascertain whether a gift contract exists. Furthermore, the contract form cannot serve a good signal to tell the good promisor from the masquerader. A donor's right of regret should not be forfeited just because her gratuitous promise was written down on a piece of paper. However, a bank check is another thing. With the insights from economic analysis, this paper hopes a better understanding on donor's right of regret can be established.