We prepared high purity, fine tungsten carbide powder using a chemical solution composed of tungstic acid, citric acid and ammonia solution. Precursor powder, obtained by spray-drying the chemical solution, was heated under argon to 1423 K. Total carbon of the heat-treated precursors was controlled by adjusting the molar ratio of citric acid and tungstic acid. The carbonization temperature was lower than conventional methods using carbon and tungsten trioxide or tungsten, therefore grain growth was suppressed. The grain size of obtained tungsten carbide was approximately 100 nm. Impurities (iron and cobalt) were less than 10 ppm.