<p>The present invention relates to an abrasive containing a slurry in which cerium oxide particles having an intensity ratio of an area of a primary peak appearing at 27 to 30° to that of a secondary peak appearing at 32 to 35° (primary peak/secondary peak) in a powder X-ray diffraction chart of 3.20 or more are dispersed in a medium. It also relates to a method for polishing a substrate with the abrasive.</p>