This study aims to extract dye and alginate from seaweed Sargassum sp. as a dye paste in the coloring of Bima woven fabric. The concentration of sodium alginate used was 0%; 1%; 3% and 5%. The results showed that the absorbance value of the dye extract from seaweed Sargassum sp at maximum λ = 203 nm obtained A = 3.899. The effect of variations in the concentration of sodium alginate in the dye paste was determined by comparing the FTIR absorption pattern of Bima woven fabrics. Based on the FTIR absorption pattern data, it was found that a mixture of dye and sodium alginate of 3% had a stronger intensity, namely the wave numbers 3448.72 cm-1 and 1635 cm-1; 2900.94 cm-1; 2337.72 cm-1; 1381.03 cm-1 and 1064.71 cm-1. The results of the morphological analysis showed significant differences in surface structure on Bima woven fabrics before and after the dyeing process.