In the substrate holder, while holding a periphery portion of a semiconductor wafer, some of protruding portions having a grass shape on a pad main body hide beneath the semiconductor wafer, and the others of the protruding portions are exposed outside the semiconductor wafer. Also, the protruding portions hiding beneath the semiconductor wafer contact a rear surface of the semiconductor wafer, and sink the semiconductor wafer to a suitable depth via gravity, thereby holding the semiconductor wafer mainly in a length direction. In addition, some of protruding portions exposed near the periphery portion of the semiconductor wafer contact a side surface of the semiconductor wafer, thereby holding the semiconductor wafer mainly in a width direction.