Abstract: Disclosed is an ink holding material to be put in an ink tank of an ink jet recording device, which is such that when it is extracted with pure water, the electrical conductivities and the surface tensions of the water before and after the extraction satisfy relationship (1):350 .gtoreq..gamma.r/.sigma.r-.gamma.s/.sigma.s.gtoreq.0 (1)wherein .gamma.r represents the surface tension (mN/m) of pure water before extraction; .sigma.r represents the electrical conductivity (mS/m) of pure water before extraction; .gamma.s represents the surface tension (mN/m) of pure water after extraction; and .sigma.s represents the electrical conductivity (mS/m) of pure water after extraction.

Abstract: Ink-jet recording ink comprising water, a water-soluble organic solvent and a color material as essential ingredients, wherein the total volume of particulate matter ranges from 1.times.10.sup.-9 to 1.times.10.sup.-2 cm.sup.3 per cm.sup.3 of ink, whereby defects in images such as blank areas on images, fluctuations in dot diameter and the disturbed shape of dots are not generated to give a prominent effect and wherein the total volume of the particulate matter existing in 1 cm.sup.3 of the ink is adjusted to 3.5.times.10.sup.-6 or less, whereby ink which is stable even after long-term use can be obtained and change in amount of ink at jetting is slight, as well as defects in images can be prevented.