A series of quaternary ammonium salts having a methyl- or a dodecylimino group or a dimethyl- or a dodecylmethylimmonio group (trisquaternary ammonium salt) between two dodecyldimethylammonio groups was prepared from dodecylamine and epichlorohydrin. Their surface-active properties such as surface tension and the foaming properties of the aqueous solutions were measured. All the prepared quaternary ammonium salts showed good water solubility, and the characteristic surface-active properties in comparison with those of the conventional monoquaternary ammonium salt as stated below. The cmc’s of the quaternary ammonium compounds with two dodecyl chains are 2 orders of magnitude lower, and those of the compounds with three dodecyl chains are 4 orders of magnitude lower compared with the conventional dodecyltrimethylammonium chloride, regardless of the number of hydrophilic ammonio groups in the molecule. There is a linear relationship between the total carbon number in the hydrophobic groups and the cmc on a semilogarithmic scale for prepared quaternary ammonium salts in the present study along with bisquaternary ammonium salts from a previous study. In the case of the quaternary ammonium salts having two alkyl chains (2a, 4a), there was a small effect of the additional charge in the center of the molecule on the foaming properties. But the trisquaternery ammonium salt having three alkyl chains and three ammonio groups (4b) shows the strong foaming ability and the good foam stability compared with that having three alkyl chains adn two ammonio groups (2b).