We prepared silver-containing hydroxyapatite (Ag-HAp) powders by an ultrasonic spray-pyrolysis (USSP) technique and evaluated their antibacterial activity. Ag-HAp powders with Ag contents of 0, 1, 2, 5, and 20 mol% as nominal composition were prepared by the above USSP technique. The droplets of starting solutions were dried at 300 °C and then pyrolyzed at 850 °C to prepare the Ag-HAp powders. Ag-HAp powders showed a HAp single phase and were composed of spherical particles with a diameter of 0.5 - 3.0 μm. To evaluate the antibacterial activity of resulting powders, colony count method was performed using Staphylococcus aureus. Ag-HAp powders with the contents of Ag more than 5 mol% showed good antibacterial activity.