In the dyebath consisting of acid- and cationic-dyes, properties of the dye solution and behavior of a non-ionic dispersing agent were investigated by the measurements of particle size of the dye aggregates and absorption spectra. Acid dyes and cationic dyes in the solution without non-ionic dispersing agent were precipitated a lot. As the non-ionic dispersing agent increased, the degree of precipitation was highly decreased. The effect of adding non-ionic dispersing agent in the dye bath was also investigated. The non-ionic dispersing agent made complex with acid dye, but not with cationic dye.