The present invention relates to a powder antifoaming agent which contains: (A) a hydrophobic organopolysiloxane that has a viscosity at 25°C of 10-100,000 mm 2 /s; (B) a fine silica powder; (C) a surfactant; and (D) a water-soluble encapsulating agent that is in a solid state at 25°C. This powder antifoaming agent is characterized by being obtained by spray drying a dispersion liquid that is obtained by dispersing a silicone oil compound, which is obtained by mixing the component (A) and the component (B), and the component (D) in water in the presence of the component (C), and is also characterized in that the silicone oil compound is encapsulated by the component (D) that serves as an outer shell. Since the powder antifoaming agent of the present invention does not contain water by being produced by a spray drying method, the powder antifoaming agent is free from problems of emulsion antifoaming agents such as separation and putrefaction, thereby exhibiting extremely excellent storage stability.