議會制國家的立法與行政是既結合又對抗的關係，其結合關係表現在政府的成立與存續完全依賴國會的信任，對抗關係則表現在倒閣與解散國會的兩個制度設計上。倒閣是國會通過不信任投票的後果，解散國會的原因則是政府的信任案被國會否決。由於政黨政治的成熟，議會制國家的政府首長通常也是國會中多數黨的領導人，遂令國會不容易對政府發動不信任投票，逕行倒閣；反倒是政府首長更容易操弄信任投票，故意輸掉信任案，以解散國會來制裁黨內的批評者以及對反對黨主動出擊，達到藉改選國會來增加席次的目的。二○○五年德國的眾議院提前改選，其結果是出現了左右共治的大聯合政府。此次改選的原因是總理的信任案被否決，因而導致了眾議院被解散。本文主要是從德國基本法的抽象規範與憲政的實際運作兩個層面，首先對信任案及其相關問題作探討，其次對因解散眾議院而來的改選與組閣的過程作詳細的分析。

In a parliamentarian country, the relationship between the administration and the legislation is both reliance and rivalry. The spirit of reliance appears on the trust of the Parliament that a government depends to exist and continue while rivalry appears on two systematic designs, the resignation of the cabinet and the dissolution of the Parliament. The resignation of the cabinet is the result of the parliamentary vote of no confidence and the reason of the dissolution of the Parliament is because the government's confidence is vetoed. As party politics prevails, in a parliamentarian country, the head of the government is usually the majority party leader in the Parliament. As a result, the Parliament is not likely to motion a vote of no confidence on the government to dismiss the cabinet; while the head of the government is more inclined to maneuver the vote of no confidence by losing it deliberately so as to dissolve the Parliament and take the chance to punish critics in the party and attack the opposition party. By forcing a reelection of the Parliament, the purpose of gaining more seats may be obtained. Germany's general election is held ahead of time in 2005 and the result is the appearance of a grand coalition government of both left and right. The reason of this reelection is that the chancellor's vote of confidence is vetoed which results in the dissolution of the Parliament. This article is to discuss the vote of confidence and its related issues based on the abstract norm of Germany's Basic Law and the actual operation of constitution first, and secondly to analyze in details the process of reelection and the formation of cabinet after the dissolution of the Parliament.