The invention discloses a coating solution for use in forming Bi-based ferroelectric thin films containing Bi, metallic element A (at least one selected from the group consisting of Bi. Pb, Ba, Sr, Ca, Na, K and rare earth elements) and metallic element B (at least one selected from the group consisting of Ti, Nb, Ta, W, Mo, Fe, Co and Cr), wherein it contains metal alkoxides of Bi, metallic element A and metallic element B respectively, and contains composite metal alkoxides formed by any two or more of said metal alkoxides; and a ferroelectric thin film, a ferroelectric capacitor and a ferroelectric memory formed by the use of such coating solution, and a method for producing the same.