The objective of the present invention is to provide a method for preparing a cationic electrodeposition coating composition that contains a bismuth compound and exhibits excellent coating material stability, curability, coating film appearance and the like. The present invention provides a method for preparing a cationic electrodeposition coating composition, which comprises a step for mixing a resin emulsion (i) and a pigment-dispersed paste, and wherein: the resin emulsion (i) contains an aminated resin (A) and a blocked isocyanate curing agent (B); the pigment-dispersed paste contains a bismuth mixture (C) that is obtained by mixing a bismuth compound (c1) and an organic acid (c2) in advance, a pigment-dispersed resin (D), an amine-modified epoxy resin emulsion (ii) that contains an amine-modified epoxy resin (E), and a pigment (F); the pigment-dispersed resin (D) has a hydroxyl number of 20-120 mgKOH/g; and the amine-modified epoxy resin (E) has a hydroxyl number of 150-650 mgKOH/g.

The objective of the present invention is to provide a method for preparing a cationic electrodeposition coating composition that contains a bismuth compound and exhibits excellent coating material stability, curability, coating film appearance and the like. The present invention provides a method for preparing a cationic electrodeposition coating composition, which comprises a step for mixing a resin emulsion (i) and a pigment-dispersed paste, and wherein: the resin emulsion (i) contains an aminated resin (A) and a blocked isocyanate curing agent (B); the pigment-dispersed paste contains a bismuth mixture (C) that is obtained by mixing a bismuth compound (c1) and an organic acid (c2) in advance, a pigment-dispersed resin (D), an amine-modified epoxy resin emulsion (ii) that contains an amine-modified epoxy resin (E), and a pigment (F); the pigment-dispersed resin (D) has a hydroxyl number of 20-120 mgKOH/g; and the amine-modified epoxy resin (E) has a hydroxyl number of 150-650 mgKOH/g.