Abstract: A process for obtaining an aqueous fumaric acid solution which is useful in stably obtaining a large amount of aqueous fumaric acid solution. A column is packed with solid fumaric acid and then water is passed through the column, thereby giving an aqueous fumaric acid solution. Water is usually passed in the reverse direction. The solid fumaric acid may be in the form of tablets containing 70% by weight or more of fumaric acid. The aqueous fumaric acid solution thus obtained has a pH value of about 1 to 4. A urinal, etc. is treated with a fumaric acid-containing deodorizing agent to thereby efficiently deodorize nitrogen-containing bad-smelling components over a long period of time. A solid deodorizing agent containing fumaric acid, which has an extremely low solubility and a low dissolution rate in water, is placed on a urinal to deodorize the same.