The article aims to show how Foucault, who refuses the pro-Marxist tradition, and builds his works on a genealogical basis, approaches to power relations. In his works, Foucault grounds arguments on subject and uses the power phenomenon as an instrument to show how a subject has historically turned to an object. Power relations become visible through subjective experience (insanity, delinquency, sexuality, death, and so on). The notion of governmentality, the result of the role of subject as the main factor in public administration issue, telling the transition period of the medieval states of justice into administrative states, is an expression of power relations. It could be suggested that a government, which employs tools for knowledge for the sake of governmentality corresponds to a society controlled by security devices.