The progress of the Internet of Things (IoT) has enhanced real-time accessibility on smart things, and the advent of online social network (e.g. Facebook, Twitter, and Google+) have attracted people in sharing their knowledge and experiences with their social organization. Recently, several researches have shown that online social network could act as a user interface of smart things and smart things could be shared by using online social network, and especially we expect that the integration of both of them provide us with novel services which we collectively call IoT social network. However, it is possible that developers or researchers will address complexity of jointly utilizing and understanding both. In this paper, we propose a novel social networking platform for the Internet of Things, called Lilliput. Lilliput is an ontology-based platform providing information of online social networks (e.g. people's profiles, people's social relationships) and smart things (e.g. context, location) as a social graph. To architect consistent unified ontology-based platform, we conduct a research on what the social relationship among people, objects, and places will be, and propose it as IoT social relationship. Also, we show how to exploit this ontologically-connected people, objects, and places by mainly focusing on Human-oriented Access Control for IoT social network (HAC). With this platform, application developers can build IoT social network application without having to understand details in both online social networks and the Internet of Things. We show the feasibility of our architecture by implementing a prototype platform, building a testbed, and creating one of IoT social network applications, called Sorcerer's Book.