Over the past several decades, more and more social activities happen in places which are privately owned. Scholars have called these properties ‘mass private property’ (MPP): the private properties that are open to the mass. However, while MPP arouses scholars’ attention and interest, there is not a clear understanding of what type of physical space is a ‘mass private property’. Rather, the concept of MPP is usually used in an intuitive and taken-for-granted way without examining the ideal essences of diverse MPP spaces. This essay clarifies the criteria by developing the ideal type of MPP. Although MPPs are diverse, to some extent they should share the ideal-typing features of real-estate, legal and sociological dimensions.