It is an object of the present invention to provide an emulsion which can form a coating excellent in water penetration resistance as well as impregnating adhesion property, its production method, and a structure body using the emulsion. The present invention is directed to an emulsion comprising a hydrophobic resin particle (A) dispersed in a water-based medium as a resin component, wherein 20 to 60% by weight in the entire resin components including the hydrophobic resin particles (A) is a polymer emulsifier (B) and the average particle diameter of the particles contained therein is 50 nm or smaller.