My primary aim in this essay is to clarify the notion of a moral reason. To accomplish this, I criticise in the first section the main conceptions of moral reasons. In the second and third section, I explain my account of moral reasons, arguing that moral reasons are a kind of social reasons, and illustrate it by examples. Although the concept of a moral reason is central to our moral thinking; it has received scant attention in the philosophical literature. Furthermore, it is a very unclear notion and causes confusions in ethical debates. It has always been an objective of analytic moral philosophy to clarify perplexing notions, and this paper attempts to contribute to this goal.