PURPOSE: To readily detect the protein other than albumin by impregnating an absorbing carrier with a buffer giving the acidic condition, a dye generating a color tone change under the existence of the protein, and & material generating heat with an aqueous sample, and reacting it with the aqueous sample at a specific reaction temperature.

CONSTITUTION: The reaction temperature is preferably set to the range of 30-50°C, and the reactivity of the protein other than albumin, particularly Bence- Jones protein, is remarkably improved in this temperature zone. The reaction condition of 30-50°C is obtained by the following methods: a material generating heat when reacted with urine is mixed, a heated sample is used, the sample is reacted in the preset temperature environment, or the test is conducted on a heated plate. Calcium chloride, calcium bromide, magnesium chloride, zinc bromide, or zinc chloride is used for the material generating heat when reacted with urine, for example.