The objective of this study was to attain extensive understanding of acting in the Elizabethan Age based on the influential relationship between the oratory of rhetoric and actors’ acting in the Renaissance Age. In the Renaissance Age, rhetoric restored an important position again through the rediscovery of the classics pursued fiercely by the humanists. Petrarca’s discovery of Cicero’s oration manuscripts and Quintilianus’ discovery of a manuscript version of 『Institutions of Oratory』 raised people’s interest in oratory and played a decisive role in the development of rhetoric. Beginning with domestic changes, England was influenced by Erasmus’ visit to the country and English humanists’ studying in Italy. Like the ultimate goal of rhetoric to Cicero and Quintilianus was great oratory, rhetorical research in the Renaissance Age was not theoretical but a part of practical life. Accordingly, a good use of words meant the possession of wisdom and keen discernment, and oratory was the best means to exhibit the quality. Actors’ acting in the Elizabethan Age were similar to actio in rhetoric. That is, actors’ speech was delivered to the audience by customary gestures and voices according to rhetorical principles. Customary gestures were those classified as adequate for each emotion, with which actors should be able to produce exact voices and gestures corresponding to the writer’s idea. This could be attained from thorough understanding of lines and ability to ‘adapt word to the actor’s action, action to his word, and pronunciation to the former two’ as explained by Heywood. Actors’ acting as such came from the influence of oratory with which people could read others’ thought or emotion through gestures, and suggests that people who had rhetorical education from a young age were somewhat familiar to encoding actors’ gestures. However, what is important in actors’ acting was not simply copying stereotyped frames but expressing pleasantly, vividly, and naturally by inserting their personality. It reads “If one wants to give authenticity to his words the words should carry the speaker’s genuine emotion” in Volume 6 of Quintilianus’ 『Institutions of Oratory』. Like this, actors’ acting must be based on ‘genuine emotion.’ In the Elizabethan Age, 『Institutions of Oratory 』 was used as a textbook in most of schools, and exerted enormous influence on rhetorical theories and on every aspect of oratory. The importance of Quintilianus’ argument suggests that orations and actors’ acting in the Elizabethan Age could not be exaggerated. It is concluded, accordingly, that actors’ acting in the Elizabethan Age surely consisted of customary gestures, that they should be expressed extremely naturally, and that only voices and actions based on ‘genuine emotion’ could be expressed naturally.