An ink jet printing penetrant which is used to penetrate an ink jet printing color ink containing a dye in a cloth is provided, and the inkjet printing penetrant includes at least one glycol-based solvent having an HSP value of 13.6 or more; and water. In addition, the content of the glycol-based solvent with respect to a total mass of at least one organic solvent contained in the ink jet printing penetrant is 95 percent by mass or more, and the glycol-based solvent has a standard boiling point of 243°C or less.