This paper examines the possibilities and the limitations of applying Speech-Act Theory to historical research based on inscriptions. Inscriptions are an essential source for any research of ancient history. In recent years, an increasing number of researchers have studied inscriptions not only as literary sources but also as monuments. Subsequently, we need to examine inscriptions from a wider variety of perspectives than the literary sources of ancient writers. Since the 1990s some scholars of inscription texts have tried to introduce Speech-Act Theory, developed by linguistic philosophers, into their study of ancient history. Speech-Act Theory addresses the ways in which words can carry out actions through their sense, not perform an action in and by words. Until now it has been argued that the two essential factors of an inscription are its eternity and its accessibility. Based on these elements, if we view an inscription through Speech-Act Theory, we realize that inscriptions were a more dynamic medium than literary sources. Although there are some limitations, such as the ancients' perception of inscriptions, their literacy and the range of applications of the theory, this paper insists that with their spatial occupation as monuments, inscriptions functioned to exert power widely throughout a society, by means of influencing others and changing the world through speech-acts.