An antibacterial agent composed of silver-containing aluminum sulfate hydroxide particles represented by the following formula (X-I) or (Y-I). €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ(Ag a B b-a ) b Al cA (SO 4 ) y (OH) z ·pH 2 O€ƒ€ƒ€ƒ€ƒ€ƒ(X-I) €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ[Ag a B b-a ] b [Ti 3-c Al c ] (SO 4 ) y (OH) z ·pH 2 O€ƒ€ƒ€ƒ€ƒ€ƒ(Y-I) The above antibacterial agent of the present invention provides antibacterial molded articles and further antifungal agents, cosmetics, antibacterial paper, antibacterial deodorizing sprays and agricultural chemicals when it is mixed with a resin.