This study will survey the significance of theatre in the philosophy of the contemporary French philosopher, Alain Badiou. He is probably the only philosopher in the contemporary world who still regards philosophy as a search for truth. He first mentions four domains of science, politics, art, and love, which are, in a way, reminiscent of Plato’s divisions regarding human and the world. He claims then that truths are produced only in these four domains. As regards the art of theatre, he has theses and ideas unconventional and uncommon to the worlds of art and philosophy, whose understanding requires, to a great extent, an acquaintance, even though elementary, with the main concepts of his intellectual and philosophical system. For Badiou, the event of true theatre is a kind of collective and communal creative act which creates its own specific subject, and in each staging of the theatrical text, the inner idea of the text completes. Badiou believes that theatre thinks, and, even though it is to a great extent dependent on the state, it can and should try to reveal its limitations, to create its own theatrical subject, and to form a new change by creating something new. In the end, it must be noted that the starting point of this discussion is philosophy, and this essay proceeds from Badiou’s philosophy toward the art of theatre.