The present invention provides a softening base and a softener having biodegradability employing a quaternary ammonium salt composition comprising (M) a monoester quaternary salt represented by the formula (I), (D) a diester quaternary salt represented by the formula (II) and (T) a triester quaternary salt represented by the formula (III), wherein the amount of (M) is 15 to 85% by weight, the amount of (D) is 0 to 44% by weight and the amount of (T) is 15 to 85% by weight based on the total amounts of (M), (D) and (T). The present invention also provides a process for producing the softener base and composition. ##STR00001## wherein R, R.sup.1, n and X.sup.- are defined herein.