To provide a water soluble cutting fluid capable of obtaining slurry having excellent lubricating property without increasing the viscosity of the slurry and abrasive grain slurry containing the same.

The water soluble cutting fluid contains a copolymerizable polyether (A) obtained by adding tetrahydrofuran and a 2-3C alkylene oxide to a 24C compound (a) having 1-8 active hydrogen atoms in one molecule. The abrasive grain slurry is formed by containing the water soluble cutting fluid and the abrasive grains having 1-50 m volume average particle diameter, wherein the weight ratio of the water soluble cutting fluid to the abrasive grain is (1:0.5) to (1:2).