In this study, the place and uses of the interrogative particle "mI" in Tuḥfetü'l-İḫvān which is one of the 15th century works have been examined. Interrogative suffix/postposition in Turkey Turkish has been analysed in terms of its location and uses in the introduction part of the study. This element is considered by the researchers as suffix, postposition, adverb, and exclamation. Essentially, in fact, it is mostly accepted that it is derived from postposition and subsequently becomes an addition. The interrogative particle is one of the widest suffixes among the particles. They are brought to names and verbs. The location of shooting varies according to the person and the code. The interrogative particle whose main function is to establish interrogative sentences contributes to various functions and meanings in terms of its usage and location in the sentence such as questioning, obscurity, suggestion, anger, fear, confusion, ridicule, humiliation, condemnation, contempt, persuasion, challenge, counselling, questioning, doubt, praise, despair, criticism, and defence. In Tuḥfetü'l-İḫvān, this particle has been used in 144 locations. In a sample, unlike the orthography of the era, it is in the form of "mü". This suffix/postposition has been identified with various meanings and functions in the work. Paying attention to the usage of the interrogative sentence following the element which is to be emphasized in particular is striking in the study. It is especially noteworthy that this particle is used as a gerundium. In the beginning, this element, which is only used for question / exclamation, has gained different functions and meanings over time as well as the function of interrogation. Uniformity of expression is changed by altering the position in the sentence, and the sentence is used in various functions ranging from adding various meanings. It can be easily predicted that new functions/usages can be included as a requirement of the vitality of language.