One object of the present invention is to improve the uniformity of polishing in a substrate polishing device for polishing a quadrilateral-shaped substrate.
The present application discloses, as one embodiment of the present invention, a substrate polishing device (100) for polishing a quadrilateral-shaped substrate (130), the substrate polishing device (100) including: a surface plate (110); a substrate support mechanism that is attached to the surface plate (110) and that supports the substrate (130); a polishing head mechanism (140) for attaching a polishing pad (150), the polishing head mechanism (140) opposing the surface plate (110); and an orbital drive mechanism (160) for orbitally driving the polishing head mechanism (140). The substrate support mechanism includes: a base plate (121); a plate flow passage (520A, 520C, 520E) provided to the base plate (121); and a plurality of substrate support chambers (510A, 510C, 510E) that are connected to the plate flow passage (520A, 520C, 520E), wherein each substrate support chamber (510A, 510C, 510E) independently applies a vertical direction force to the substrate (130), and the vertical direction force applied to the substrate (130) corresponds to an internal pressure of the substrate support chamber (510A, 510C, 510E).