購併背後通常隱含著巨大的組織變革，留存的被併公司員工儼然就像是新進員工面臨剛就職的組織，充滿著陌生和不確定感。因此，本研究引入新進人員適應議題中經常運用到的期望符合度概念，並納入員工知覺組織支持的概念，探討員工在購併後所產生的期望落差和所知覺到組織關心自己的程度，對其組織承諾與壓力感受的影響。本研究選定半年至兩年內之購併案進行研究，對購併過程中較少機會參與協商與決策的中階管理階層以下之留任的被併公司員工進行問卷調查。研究發現購併後被併公司員工對新公司的工作規定和相關福利措施，乃至於個人與整體組織的配適可能會產生期望落差。而此種期望落差會對員工的壓力感受與組織承諾產生影響。期望落差除了對員工的組織承諾和壓力反應有直接的影響效果外，還會透過員工對組織支持的知覺，間接影響到員工的組織承諾。

Mergers and acquisitions usually imply enormous organizational changes. The acquired employees feel unfamiliar and uncertain just like the newcomers to an organization. This study explores the unmet expectation of the acquired employees how to affect their work attitude and job stress after mergers. In addition, this study also discusses the role of perceived organizational support in the relationships among the met expectation, job stress and organizational commitment. Considering the impact of mergers and acquisitions on the acquired employees are greater than the acquiring ones, especially the employees under the middle management level, we selected the remained employees under the middle management level in the corporation acquired less than 2 years as the sample. This empirical study found that the unmet expectation of acquired employees not only from job regulations and benefit, but also from the person-organization fit of the acquiring corporation. The unmet expectation may both affect the psychological and behavioral stress of acquired employees. It also affects the organizational commitment of acquired employees to the acquiring corporation. The unmet expectation has a direct effect on the job stress and organization commitment. It also has an indirect effect on the organizational commitment through the perceived organizational support.