Viscoelastic behavior of aqueous solutions of a cationic surfactant, cetyltrimethylammonium p-toluene sulfonate (CTApTS), and an organic salt, sodium p-toluene sulfonate (NapTS), was examined at room temperature by changing concentrations of CTApTS (C D ) and NapTS (C S ). CTApTS forms long threadlike micelles in aqueous solution even at low C D in spite of the absence of additives. Aqueous CTApTS solutions show pronounced viscoelastic behavior, which is perfectly described by Maxwell model type viscoelasticity, keeping a single set of relaxation parameters (G N and τ). The magnitude of relaxation strength, G N , is proportional to the square of C D irrespective of the value of C S . The value of a relaxation time, τ, is independent of C D , while the value remarkably reduces with increasing concentration (C S * ) of excess pTS - ions in the bulk aqueous phase. The relationship between τ and C S * for the system is not identical with that for aqueous solutions of cetyltrimethylammonium bromide (CTAB) and NapTS at C S * <30 mmolkg - 1 . However, the relationships between τ and C S * for these systems agree well with each other at C S * >=30 mmolkg - 1 . This implies that formed threadlike micelles in both systems have similar structure and the relaxation mechanism is controlled by C S * , but not influenced by the presence of Br - ions above C S * =30 mmolkg - 1 .