[Problem to be Solved] To provide a method of treating a sealing compound that can efficiently separate and recover a used sealing compound into rubber latex and a liquid constituent, and also simplify the treatment of the rubber latex and liquid constituent separated from the used sealing compound. [Solution] Provided is a method of treating a sealing compound, in order to recover from the inside of a pneumatic tire the sealing compound that was used for repairing a puncture, the sealing compound including an aqueous solution having at least rubber latex dispersed therein, the method comprising: solid-liquid separating, by injecting a treating agent into the inside of a pneumatic tire into which the sealing compound was injected, the treating agent comprising at least one of a salt that is a reaction compound of an acid and a base and/or a water-soluble organic solvent, mixing the treating agent with the sealing compound inside the pneumatic tire, and aggregating and solidifying the rubber latex in the sealing compound.