This study investigates the dyeability of soybean protein fabric after dyeing with gallut. In this study, the colorants of gallnut were extracted with boiling water at $60^{circ}C$ and 60min. Soybean protein fabric was dyed with extracted solution from gallnut according to concentration, temperature and time. After dyeing with gallut solution, dyeability (K/S) was obtained by CCM observation. Al, Cu and Fe were employed as a mordanting agents. Various color changing were produced by the interactions of mordants that were different from soybean protein fabric; however, Al mordant was not indicated as a variable color change. Fastness to washing and light were also investigated. Consequently, the dyeability of the soybean protein fabric dyed with gallut showed reasonable results at 100% o.w.f, $90^{circ}C$, for 60min. Fastness to washing according to concentration indicated good result as more than grade (4-5) in general. Fastness to light was almost the same compared to fastness to washing at all concentrations. Fastness to washing according to mordants indicated good grade (4) in principle at Al, Cu, and Fe; in addition, fastness to light indicated a good grade too. Fastness to light also indicated the highest dyeability at Fe mordant. This study shows that gallut is a reasonable dyestuff to soybean protein fabric and that it is possible to manufacture a variety of products that use soybean protein fabric.