The present thesis has two questions. The one is 'What is the Noh-flower?' and the other is 'What to do to know it?' The answer of the first question is the analogy, or psychological and logical resemblance between the real- and the noh-flower. The psychological proposition, here, is that the flower, novelty and interest are all the same, and the logical ones are that both the real- and the Noh-flower are transient, and are not permanent existence. The answer of the second question is the methodology of knowing the Noh-flower. There are two problems here. The first is that what is it to know the Noh-flower and then the second is what to do to know it. To know the Noh-flower is to know oneself and to become the flower itself, because the actor is born with the potentiality to become the flower. This is the answer to the first question. To exercise heavily and earnestly, according to the "catechism of the Noh-flower" for meditation and practice, there are introduced ten catechetic questions and answers of the Noh-flower. The above mentioned articles are what I have been reading and learning in Zeami's 'Kwadensho' for forty-five years since 1929.