Method for producing native protein fiber

The original protein fiber of the present invention is an original protein fiber having 0 to 100% by mass of silk fibroin and 100 to 0% by mass of a polypeptide derived from spider silk protein when the protein fiber is 100% by mass. The original protein fiber contains an original dye. This fiber is prepared by dissolving or dispersing the original dye in the solvent used in the spinning solution or dissolving or dispersing in dimethyl sulfoxide to obtain a colored solution, and adding the amount of solvent necessary for the spinning solution to the colored solution, Protein powder is added to the solvent and dissolved to obtain a spinning solution (6), which is obtained by wet spinning or dry wet spinning. This provides an original protein fiber that can be produced at a low cost, and in which the original dye is uniformly dispersed in the fiber and can express a vivid color tone, and a method for producing the same.