質詢，是立法機關監督行政機關的利器。我國憲政體制獨樹一格，與其他國家有相當大的差別；我國憲法採行五院制，規定行政院向立法院負責，據此立法委員質詢的對象僅限於行政院及所屬機關，質詢的範圍亦應限於行政院的職掌；其他諸如總統府、司法院、考試院、監察院等單位，皆不在立委質詢的範圍內，由質詢範圍的廣狹，不但可作為委行使職權的界限，同時也可由此辨明行政院的主管權責。立委質詢的方式可分成口頭質詢與書面質詢兩種。由於立委口頭質詢適用的場合僅限於立法院院會(委員會)進行總質詢、預算質詢及專題質詢之時，書面質詢則無比限制，適用範圍較口頭質詢為廣，因此本文嘗試由立法委員的書面質詢及行政院對立法院的答復一一尤其是對第二屆立法委員書面質詢的答復為例，分析探討質詢權的適用範圍。 Interpellation is an effective tool of the legislative bodies to monitor the administration of agovernment.The constitutional syrstem of Republic of China is unique and different from those of other nations in the world. The constitution consists of five-yuan system in which the Executive Yuan is responsible to the Legislative Yuan. The legislators, according to the right authorized by the constitution, interpellate the Executive Yuan and the affiliated administrations. The compass of the interpellation of the legislator should be restricted to the responsibilities of the Executive and should not be extended to those of the President, of the Judicial Yuan, o the Examination Yuan and of the Control Yuan. Based on the compass of the interpellation, the limitations of the legislator's interpellation can be confined and the responsibilities of the Executive Yuan can be revealed as well.The interpellation of the legislator may be devided into two types, namely, the oral interpellation and the written interpellation. The former is limited to general interpellation, interpellation of national budget, and of specific issues, while the latter is exceeding those limitations of the former. This article is trying to analyze the proper compass of the legistor's interpellation based on the written interpellation of the legislator and the Executive Yuan's response to those interpellation.