行政調查中中較易影響人民權益者，為具強制性之「強制調查」。此種強制調查，固然干涉人民之權益，惟對於調查目的之實現，有其必要性。因此，如何使此種調查在法規範面獲得妥適之依據，即為本文所欲探討之重點。首先，本文將先界定行政調查之意義，以及學說上對行政調查之分類。此外，將探討行政調查基本原則之職權調查主義，以及與此有密切關係之當事人協力義務。並說明，此種協力義務之性質及原則上可否強制當事人履行。再者，將敘明行政調查中行政強制行為之意義及種類，並歸納現行法中有關直接強制調查及間接強制調查之規定，以掌握其內容。其次，關係人雖有所謂的協力義務存在，惟關係人若不配合調查時，行政機關是否得採取強制措施，以取得必要之證據？此當然涉及該調查行為究屬任意調查或強制調查之性質是否屬行政處分。且若相對人不履行時，是否得按照行政執行法之規定強制執行？若法規只有間接強制調查之規定時，行政機關是否仍可依據行政執行法上之規定，以間接強制或直接強制方法，以達到調查之目的？此皆與行政執行法有密切之關係。此外，當行政機關決定採取具強制力之直接強制調查時，由於其對人民權利干預較為明顯，因此在合法性上之要求必然較高。其次，倘法規上未明文規定得採取直接強制調查時，行政機關是否亦享有一定程度之直接強制權，以進行必要之調查？另在刑事偵查之強制處分，為避免人民權益受到侵害，乃有所謂的「令狀原則」，則此原則有無適用在行政調查中強制調查之可能？是否容許在具備一定要件下，使行政機關於聲請令狀後，亦得享有某種程度之行政搜索權？上述各點，皆與行政調查之行政強制行為有密切之關係，本文將分別探討，期有助於此方面問題之解決。

On account of “coercive investigation” of administrative investigation which is necessary to actualize investigation’s goals often infringes civil rights, this thesis attempts to discuss how coercive investigation actions builds appropriate legal basis. In the first place, we tried to define and categorize administrative investigation, and discuss the principle of investigation by authority or litigant’s petition. We also clarify the nature of the collaborative obligations and whether it could be enforced. We also described the idea of coercive investigation, and arrange valid actions of direct and indirect coercive investigation. If relevant party ignored the collaborative obligations and unconfirmed, whether administrative agency could take actions to enforce them to get requisite evidence, which depends on the nature of the investigation. Besides, if opposite party denied to perform obligation, or if the regulations were inadequate, whether administrative agency could take actions by the acts of The Administrative Execution Act? All above are closed to The Administrative Execution Act. On the other hand, the legitimacy requirements were strict inevitably while administrative agency takes direct coercive investigation actions. Could administrative agency process requisite direct investigation without regulations? Would administrative agency entitled to administrative searching privileges after pitied search warrant under the Writ doctrine of criminal procedure? This thesis attempts to offer suggestions for contributing the solutions.