Provided are a wafer holding mechanism for a rotary table and a method and a wafer rotating and holding device, which enable change of a holding position of the wafer during spin processing while maintaining the posture of the wafer, enable reduction of marks of outer peripheral pins due to etching, and enable reduction of insufficient cleaning or uneven cleaning. The wafer holding mechanism for a rotary table comprises a rotary table configured to hold a wafer on an upper surface thereof, and a plurality of movable outer peripheral pins provided in the rotary table and configured to hold an outer periphery of the wafer. The plurality of movable outer peripheral pins comprise a plurality of first movable outer peripheral pins and a plurality of second movable outer peripheral pins configured to hold the wafer at positions different from positions at which the wafer is held by the first movable outer peripheral pins. Holding positions of the wafer are changed by switching holding of the wafer by the first movable outer peripheral pins and the second movable outer peripheral pins during wafer processing.