Disclosed is a novel antibacterial ceramic product which has a high antibacterial metal use efficiency and therefore can provide a satisfactory antibacterial property even when the antibacterial metal is used in a reduced amount compared to a conventional one. Also disclosed is a ceramic surface treatment agent which can be used for the production of the antibacterial ceramic product.Further disclosed is a method for producing an antibacterial ceramic product by using the ceramic surface treatment agent. The antibacterial ceramic product has, on its surface, a metal nanoparticle which comprises at least silver and has an average particle diameter of 200 nm or less. The ceramic surface treatment agent comprises a metal nanoparticle dispersed in a dispersion medium in a colloidal form, wherein the metal nanoparticle has a 90% accumulated diameter (D90) in the particle size distribution of 150 nm or less. The method for producing the an antibacterial ceramic product comprises the steps of applying the ceramic surface treatment agent onto the surface of a ceramic product and firing the ceramic product at 800 to 1600°C.
