Abstract: A CMP polishing liquid for polishing an insulating material, comprising a cerium oxide particle satisfying the conditions (A) and (B) below, a 4-pyrone-based compound, and water: condition (A): an average particle diameter R of the cerium oxide particle is 50 nm or more and 300 nm or less, and condition (B): when the cerium oxide particle is defined as a spherical particle having the average particle diameter R, sphericity S2/S1 provided by a specific surface area S1 of the spherical particle and a specific surface area S2 of the cerium oxide particle measured by the BET method is 3.15 or less.