Mir'ât-i Cünûn is written at a time when classical Turkish literature works fed by tradition began to give way to new types of poetry and prose that developed under the influence of Western literature. Yenişehirli Avnî Bey (1826Bey ( /27-1883, who died before completing the work, was a poet who grew up with the Mevlevi culture and was in favor of innovation. In this context, it is seen that even though written in the mesnevi form, Mir'ât-i Cünûn differs from the classical mesnevi in its external structure and does not exactly match the hezel genre in which the author included it. Although it is among the humorous works in the classical genre classification and is written with a humorous style, it can be said that this mesnevi is a literary work in which seriousness is really meant. On the other hand, it is known that beyond entertainment, humor is not far from seriousness with its functions such as educating, teaching, and destroying by ridiculing. Humor theories such as superiority, opposition and relaxation that are put forward to explain how and why people laugh, also reveal the relationship between laughter and humor and seriousness. In this study, the concept of humor will be investigated in the context of the relationship between laughter/humor and seriousness, insanity and sainthood, hezel and irony in Mir'ât-i Cünûn, which is an ironic text, because the subject of the contradiction between reason and insanity is at the center.