The main aim of this chapter is to clarify the cultural significance and impact of a Korean article concerning Irish drama and theatre that were written and published in 1935. Yoo, Chi-Jin`s `Sean O`Casey wa- Na: Naega Sasookhanun Naeoui Jakga (Sean O`Casey and I: The playwright who guided my way)` was one of the most significant articles for many reasons. At the start of the article, Yoo, did not hesitate to confess to Sean O`Casey`s influence on his plays. Considering Yoo, Chi-Jin was the central figure of the modern Korean theatre movement from the 1920s onward, it can therefore be said that O`Casey`s drama and his philosophy widely influenced the modern Korean theatre movement through Yoo, Chi-Jin, and this article providesclear evidence. Furthermore, Yoo, Chi-Jin regarded his plays as creative adaptations of O`Casey`s masterpieces rather than his own original work. He even revealed O`Casey`s influence on him more clearly by comparing the characters in his plays with those of O`Casey. The most significant point is that Yoo, Chi-Jin`s admiration for Sean O`Casey was not merely limited to his technical achievements but approached total intimacy with his work. In his autobiography, Yoo, confessed that he felt strong sympathy with O`Casey`s view of life, philosophy and even political ideology. Yoo, Chi-Jin found an ideal example of how to deal with nationalistic themes and how to dramatise a political creed in O`Casey`s drama. Despite its ceaseless effort, the modern Korean theatre movement in the early 1930s mainly appealed toa small group from the urban intelligentsia while not attracting the wide support the leaders had expected. Yoo, Chi-Jin accepted that the responsibility for this situation mainly belonged to the Korean dramatists who did not attract the audience through their drama. Yoo, Chi-Jin understood that most Korean dramatists had no concept of differentmethods of expression in the theatre such as acting, scenery and sound effects. This meant that theyput all their effort into writing plays and as a result the majority of the Korean dramatic texts were written without considering stage mechanisms. As a dramatist who had acting experience, Yoo, Chi-Jin emphasised the necessity of practical training for the Korean dramatists in order to produce successful drama. To Yoo, Chi-Jin, this was the most urgent task in the efforts to improve modern Korean theatre.