Discussed is a substrate chuck for self-assembling micro LEDs. The substrate chuck can include a first frame having a hole at a central portion thereof, a second frame having a hole at a central portion thereof and disposed to overlap the first frame, a frame transfer part configured to transfer the second frame so that the second frame presses the substrate while the substrate is disposed between the first and second frames, and an auxiliary clamp configured to additionally press the second frame toward the substrate while the second frame is pressing on the substrate.