enhanced as the amount of the abrasive increases the co removal rate tends to be enhanced in addition the abrasive is preferably present in an amount by mass of the polishing composition of equal to or less than 20 and more preferably present in an amount of equal to or less than 10 a dispersion property of the abrasive in the polishing composition tends to be enhanced as the amount of the abrasive decreases in another embodiment an average primary particle size of the abrasive is preferably equal to or greater than 5 nm more preferably equal to or greater than 7 nm and still more preferably equal to or greater than 10 nm the co removal rate tends to increase as the average primary particle size of the abrasive increases in addition a value of the average primary particle size of the abrasive can be calculated based on a specific surface area of the abrasive measured by the bet method the average primary particle size of the abrasive is preferably equal to or less than 150 nm more preferably equal to or less than 110 nm and still more preferably equal to or less than 100 nm it tends to facilitate obtaining a polishing surface with fewer defects such as scratches by polishing a polishing target as the average primary particle size of the abrasive decreases in another embodiment an average secondary particle size of the abrasive is preferably equal to or less than.