PROBLEM TO BE SOLVED: To provide a method capable of detecting modified albumin and low molecular protein in a urine inspection method of early stage nephropathy for example, in addition, detecting trace protein with high sensitivity, detecting various kinds of protein in a uniform state, and capable of easily adapting to an automatic analyzer, and an inexpensive agent used for the method and used as a normal protein measurement agent.SOLUTION: Provided is a quantitative method of total protein in a liquid sample, comprising the steps of: coordinating the metal on the protein by adding metal and making the sample an alkaline state; and binding the metal chelator by chelate binding to the metal coordinated on the protein by making the acquired sample a neutral state, and adding at least one metal chelator selected from chrome-azurol B, chrome-azurol S, pyrogallol red, bromo pyrogallol red and 5-Br-PAPS.
