當事人的締約意思──效果意思或表示意思

契約之成立，除當事人意思表示合致外，必須當事人具有受契約拘束之意思。此項締約意思，表現於當事人的意思表示之中。學界通說認為，意思表示的主觀要素（效果意思與表示意思）並非意思表示的成立要件，致使意思表示的成立要件僅剩外部的表示行為，當事人的締約意思無所附麗，顯非妥當。
本文認為，效果意思固非意思表示的成立要件，但表示意思應為意思表示的成立要件，而構成當事人的締約意思。又表示意思應包含主觀上或客觀上的表示意思，必須當事人既無主觀上亦無客觀上表示意思，其意思表示始不成立。

A contract is established where the parties have an intent to be bound by a contract in addition to an agreement between them. The intent to be bound is manifested by the declaration of intention of the parties. Under the prevailing comment of scholars, the subjective elements of the declaration of intention (i.e., the intent of effect and intent of declaration) are not the fundamental requirements to set up a declaration of intention. The end result is that the only requirement to establish a declaration of intention is the external act of the parties, without taking into account of the parties’ subjective intents. This conclusion is contradictory to the basic idea that a contract can be established only after the parties are willing to be bound by it.
This paper contends that where the intent of effect is not the basic requirement of a declaration of intention, the intent of declaration is such a basic requirement, which demonstrates the parties’ willingness to be bound by a contract. The intent of declaration includes both a subjective and an objective intent of declaration, with the latter being judged by the good faith and social customs. As a result, a declaration of intention cannot be established where a party has neither a subjective nor an objective intent of declaration.