We can compare Hopkins and Dickinson, interestingly from the view point of their being called pioneers of modern poetry. We can find an important common point in their loneliness; both of them had felt deep solitude in their whole lives. Hopkins was a Catholic priest which caused loneliness and separation from other people in the Victorian English society. In that society, it was a great accident to convert to Catholicism, which means separation even from his family and friends. For the last 5 years in Ireland, Hopkins had fallen in deep dejection because of his ill health and spiritual conflict on all subjects and it expressed even his resentment to God. How vulgar and greedy people were flourishing so much while he, who had devoted his whole life to God`s purpose, was defeated and fallen in deep depression? Dickinson is different in the character of the loneliness. She decided herself to be a solitary being. She strongly refused to follow the strict Puritan tradition, which has been the spirit of her family. She did not avoid love without marriage, and even fell in love with her father`s friend. Briefly speaking, she rejected all custom and tradition of New England in the 19th century. Thus in her poems we can read her private love and solitary seclusion and resentment to the secular society. And she rejected all the traditional poetic skill and emotion, even imagined the death of herself and sneered at the affectation of other people. These two poets were alone in their whole life and they refused the easy life of ordinary people. In this article I suggest the loneliness, which is well expressed in their poems, is one of the causes that made them called a pioneer of modern poetry.