In this study, the quality characteristics of tofu prepared with added spirulina(0, 0.25, 0.5, 0.75, and 1%). As the concentration of spirulina increased, tofu yield decreased and the pH and turbidity increased. The Hunter L(lightness) and a(redness) values of tofu decreased as the amount of spirulina increased. Phycocyanin(C-phycocyanin, allophycocyanin and phycoerythrin) contents increased according to the spirulina amount. Moreover the antioxidant activity of tofu increased as the concentration of spirulina increased($IC_{50}$ values for control was 150.7 mg/g; 1% spirulina, 82.5 mg/g). Textural properties(TPA) for hardness, gumminess, and chewiness were higher in spirulina with added tofu, compared to those of control. Regarding the overall acceptability of sensory properties, spirulina with 0.5% added tofu had the highest scores among all treatments. From these results, it was suggested that the optimal amount of added spirulina was 0.5% for the preparation of high quality tofu.