In this study, we investigated whether awareness of objects is necessary for object-based guidance of attention. We used the two-rectangle method (Egly, Driver, & Rafal, 1994) to probe object-based attention and adopted the continuous flash suppression technique (Tsuchiya & Koch, 2005) to control for the visibility of the two rectangles. Our results show that object-based attention, as indexed by the same-object advantage--faster response to a target within a cued object than within a noncued object--was obtained regardless of participants' awareness of the objects. This study provides the first evidence of object-based attention under unconscious conditions by showing that the selection unit of attention can be at an object level even when these objects are invisible--a level higher than the previous evidence for a subliminally cued location. We suggest that object-based attentional guidance plays a fundamental role of binding features in both the conscious and unconscious mind.