As a Golden Law, Kant’s “Categorical” is a concept which is rooted in the history of human thought. This principle which has the most important role in regulating the social relations in the world’s nations and its traces can be found in all religious and humane schools and branches, is stated and explained by Kant in a short sentence: “Always follow a rule that you will it to be a general law”. This rule underpins an important ethical school which is known as “Obligationism”. Although this school has attracted many scholars of ethics philosophy, there are also many critiques against it. This article aims to study and analyze “the critique of maximal categorical” in such school with regard to Islamic ethics in order to show that the attempts of those who have tried to prove the compatibility of this rule with Islamic ethics are in vain and lead to no result.