In recent years, many philosophical and neuroscientific theories of consciousness were proposed with the aim of solving the hard problem of consciousness. Giulio Tononi's Integrated Information Theory (IIT) defines consciousness as integrated information and provides an account of its quantitative and qualitative aspects based on cognitive neuroscience research (Tononi, 2004, 2008). Even if IIT covers the phenomenal aspects of consciousness, until now this theory has not been object of a philosophical analysis. In this paper I propose a categorization of IIT within the main metaphysical positions about consciousness. To do that I model a taxonomy of positions based on Chalmers (2002) descriptions of three possible strategies to face up to the hard problem: materialism (type-A and B), dualism (type-D and E) and non-reductive monism (type-F). I show that these positions and their subtypes are distinguished by respect of four basic metaphysical assumptions, that are: naturalism, the causal closure of the physical world, the existence of an explanatory gap and the existence of an ontological gap. I analyze which of these four assumptions IIT accepts and which denies and finally I conclude that IIT is compatible with type-B materialism and type-F monism. Since this positions are different under many aspects, I argue that IIT's metaphysical assumptions have to be discussed further for IIT to represent an exhaustive theory of consciousness.