Abstract: An object of the present invention is to provide a preparation method for improving the edge part rust prevention property in the preparation of a cationic electrodeposition coating composition containing a bismuth compound as a curing catalyst. The present invention provides a method for preparing a cationic electrodeposition coating composition, including a step of preparing a resin emulsion (i) containing an aminated resin (A) and a blocked isocyanate curing agent (B), a step of preparing a pigment dispersion paste (ii) containing a bismuth-metal oxide mixture liquid (C) containing a bismuth compound (c1), a metal oxide (c2), a monohydroxycarboxylic acid (c3) having 3 to 5 carbon atoms in total and a solvent; a pigment dispersion resin (D); a polyvalent acid (E); and a pigment (F), and a step of mixing the resin emulsion (i) and the pigment dispersion paste (ii).