How to interpret the nature of space is a significant topic in both our daily life and philosophy;for example,philoso-phers tend to argue whether space is a kind of reality,or whether it is merely a relation between objects,and so on.As a meta-physical view and with its unique theoretical implications,Existence Monism has encountered various difficulties in its interpre-tation of some fundamental concepts,including space,because the distinctions or differences implied by space are difficult to reconcile with the only"One"asserted by Existence Monists.This paper scrutinizes three quite similar but different kinds of Existence Monism in F.H.Bradley's philosophy,Nishida Kitarō's philosophy,and Advaita Vedānta,and then analyzes the in-terpretations of the nature of space within their theoretical frameworks,pointing out the weaknesses of these interpretations re-spectively:Bradley fails to use the concept of"contradiction"consistently,and his argument is suspicious of circularity;Nishi-da has difficulty in rationally explaining how the Absolute"Nothing"can give rise to"something",and Advaita Vedānta cannot coherently shed light on whether"Brahman"and the world are equivalent or not.On the basis of these inquiries,the paper at-tempts to summarize some weaknesses of Existence Monism itself,concluding that it is fundamentally unable to deal with the contradiction between the"One"and the"many".Such a comparative investigation will help us to transcend cultural and his-torical differences,gaining a deeper understanding of the common problems faced by different kinds of philosophies.