According to the present invention, there is provided a complex in which a carrier and a physiologically active substance are integrated, the complex being conveniently obtainable, having excellent efficiency for the integration of a physiologically active substance, and having a satisfactory membrane disruptive function promoting effect. The complex according to the present invention is formed by supporting a physiologically active substance on an aggregate of a pH sensitive carrier, wherein the aggregate is formed by aggregating under acidic conditions.
