An antibacterial agent composed of silver-containing aluminum sulfate hydroxide particles represented by the following formula (X-I) or (Y-I).(AgaBb-a)bAlcAx(SO4)y(OH)z.pH2O (X-I)[AgaBb-a]b[Ti3-cAlc](SO4)y(OH)z.pH2O (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.