The purpose of the present invention is to provide: fibers having superior safety, that can be produced easily, and are resistant to organic solvents； a raw material composition for producing said fibers； and a biomaterial containing said fibers. The fibers are produced by spinning a composition containing, (A) a condensation product obtained by condensing one or more of the compounds represented by general formula (1), and (B) an acid compound. (Each symbol in the formula is as defined in the description).
