A method of visually determining a site of origin of urine odor formation and the intensity of urine odor, wherein the method comprises a first step of applying a liquid preparation containing a component (A) to an object, facility or material to be determined on urine odor, a second step of allowing an enzymatic reaction to proceed in the object, facility or material to which the liquid preparation has been applied, and a third step of observing the change in color in the object, facility or material to which the liquid preparation has been applied, wherein a region in which the color is changed is determined as a site of origin of urine odor formation and the amount of change in color is assigned to the intensity of urine odor and a method of screening for a material, a member or a urine odor formation inhibitor each having an excellent urine odor formation inhibitory effect, or screening for a way of placing the member, wherein the method comprises bringing a liquid preparation containing the component (A) into contact with each of materials, members or agents which are subjects to be evaluated on a urine odor formation inhibitory effect, and selecting a subject that shows little change in color through an enzymatic reaction among from the above-mentioned subjects. The component (A): an enzyme activity detection reagent which can act as a substrate for an enzyme and can produce a poorly-water-soluble pigment compound or a poorly-water-soluble fluorescent pigment compound through an enzymatic reaction.
