The author has improved the method of Brom-phenol-blu (BPB) staining on filter paper (original method), and devised the spot method on filter paper pre-stained with BPB (simplified method), and the dipping method of the filter paper pre-stained with BPB (test paper method). The author has compared the quantities of minute urinary proteins by the original method on one hand, and those by the simplified and the test paper methods on the other. The quantities of the urinary protein by the simplified method coincide with those by the original method. Also, the quantities of the urinary protein by the test paper method coincide with those by the original method. The analytical sensitivity of these improved methods was 6 mg/dl of urinary protein. As the improved methods are quite simple and have a quite excellent sensitivity, it is considered to be applicable to the screening of fatigued workers.