A powder mixing system and method improves productivity of a final product by reducing time required for completion of mixing. The powder mixing system includes a mixing vessel provided with a rotating shaft for mixing multiple kinds of powder, a rotating machine for rotating the mixing vessel by means of the rotating shaft, an image photographing device for acquiring an image of the powder in a mixing process, and a computer. The mixing vessel includes a window through which the image of the powder is photographed. The computer has a function of detecting that the mixing vessel is located at a predetermined position. The image photographing device acquires the image of the powder through the window of the mixing vessel located at the predetermined position. The computer estimates a mixing state of the powder based on the acquired image of the powder.