This study An Exposition of the Idea of Slavery in Hare examined the idea of Slavery identified by R.M. Hare and offers an important foundation to slavery and utilitarianism. Some objectors to utilitarianism have tried to dismiss moral reasoning as to having any importance by blaming the awful actions of slave traders and slave owners on utilitarianism. They attack this doctrine by saying that utilitarianism is a belief system that can either praise or condemn slavery, and utilitarianism easily commend slavery if a majority of the people visualize a slave-owning society as the most beneficial and generate greatest happiness. This study describes Hares view on slavery and applies it to utilitarianism which given human nature, that masters would treat slaves humanely, and avoid a gradual corruption of their moral consciousness which would cancel out any possible advantages of the system. The major objective of this work was to do a philosophical exposition of the works of Hare on the concept of slavery. The research method adopted in this research include, the expository, analytic and critical methods. Conclusively, Slavery is commonly understood as behavior that demeans, humiliates or embarrasses a person, and it is characteristically identified by its unlikelihood in terms of social and moral reasonableness. Slavery is wrong because it violates the principles of the Declaration of Independence, which include equality, the right to life, liberty, and consent to be governed. Slavery is wrong not because it violates fundamental human rights, but because it would in practice generally increase misery.