Provided are a method of preparing a silica powder coated with an antibacterial agent and a topical dermatological composition including the silica powder, and more particularly, a method of preparing a silica powder coated with an antibacterial agent by forming a silica particle by inducing a reaction between silicon alkoxide and alcohol solvent in the presence of a catalyst and then forming an silver and metallic coating layer on the silica particle, and a method of preparing a topical dermatological composition including the silica powder. The silica powder coated with the antibacterial agent may have high antibacterial capability, and thus, topical dermatological products including the silica powder may be maintained for a long time without using a chemical antiseptic agent that may irritate the skin and cause an allergy in the human body. Even if a small amount of expensive silver (Ag) ion material is used, the silica powder has excellent antibacterial capability and stability. In addition, since the silica powder exhibits bright color, colors may be freely expressed when used in a composition of cosmetics, and thus, there is no is limit in using the silica powder in bright-color cosmetics as well as in dark-color cosmetics.