PROBLEM TO BE SOLVED: To provide a method for preventing solidification of granulated blast furnace slag which can prevent solidification of granulated blast furnace slag over a long period of time without additional equipment for sterilization treatment and complicated operation.SOLUTION: In a method for preventing solidification of granulated blast furnace slag, an agent for preventing solidification of granulated blast furnace slag in which a component for preventing solidification of granulated blast furnace slag and a rot preventing component in an effective amount for rot prevention capable of preventing rot of the solidification preventing component are mixed beforehand is diluted with water having an oxidation reduction potential (ORP) of 0 mV or more so that the concentration of the solidification preventing component becomes an effective concentration for solidification prevention, and the obtained aqueous solution of the solidification preventing agent is brought into contact with granulated blast furnace slag to prevent the solidification of the granulated blast furnace slag.
