不信任动议（英语：Motion of No Confidence 或 Motion of Non Confidence）、不信任投票（英语：Vote of No Confidence）或不信任决议（英语：Resolution of No Confidence）是一种议会的议案，传统上由反对派提交给议会，希望打败政府或使政府难堪。在少数情况下，它也可能由对政府已失去信心的昔日支持者放入议会的议程，该议案由议会投票决定通过或拒绝。一般而言，假如议会表决通过不信任动议或无法通过信任动议，政府只有辞职或解散议会并进行大选这两个选择。

A motion of no confidence (alternatively vote of no confidence, censure motion, no-confidence motion, or (unsuccessful) confidence motion) is a statement or vote that a person or persons in a position of responsibility (government, managerial, etc.) is no longer deemed fit to hold that position: perhaps because they are inadequate in some respect, are failing to carry out obligations, or are making decisions that other members feel are detrimental. As a parliamentary motion, it demonstrates to the head of state that the elected parliament no longer has confidence in (one or more members of) the appointed government.