People feel uncomfortable when someone else comes spatially near and thus encroaches on their personal space (PS). Although many social psychologists have explored characteristics of PS of/between/among individuals so far, there is currently no empirical research on whether the PS of individuals expands into space surrounding their belongings (or objects) that are away from their body. This study measured the spatial distance between bags which participants and confederates left behind, and thus demonstrated that the distance between bags was modulated in response to the interpersonal relationship of their owners. The present study suggests new evidence for expansive PS, which is the concept that an individual's PS expands into space surrounding his/her belongings.