A carbon black aqueous dispersion which has excellent dispersibility and ink performance and is suitable as an aqueous black ink for an inkjet printer or the like, and a method of producing the same. The carbon black aqueous dispersion is obtained by spraying a slurry including carbon black, a surface chemical modifier, and an aqueous medium under pressure from a nozzle to cause collision between sprayed streams or between sprayed streams and a wall surface. The carbon black agglomerates have a maximum particle diameter of 1 .mu.m or less. The production method includes mixing carbon black and a surface chemical modifier into an aqueous medium to form a slurry, and spraying the slurry from a nozzle under pressure to cause collision between sprayed streams or between sprayed streams and a wall surface to atomize and chemically modify carbon black agglomerates, thereby finely dispersing the carbon black in the aqueous medium to such an extent that the carbon black agglomerates have a maximum particle diameter of 1 .mu.m or less.