The effects of the addition of soybeans cultured by mycelia of Pleurotus eryngii (SMP) on the characteristics of tofu were studied. Protein and ash contents of SMP were higher than those of untreated soybeans: 43.23 and 6.34% for treated soybeans, respectively, and 40.42 and 5.90% for untreated soybeans. But lipid and carbohydrate contents of SMP were lower. For minor elements, Mg and Ca contents of SMP were higher and P was lower than control. Tofu could be manufactured when SMP was added below 25% to the untreated soybean. In scanning electron microscopic observation, tofu tended to break down as the ratio of SMP was over 25% to the untreated soybean. The addition of SMP $(5{sim}15%)$ increased the yield of tofu to $1.5{sim}3.5%$. In textural characteristics, hardness of tofu increased as the ratio of SMP increased up to 20%. Cohesiveness, chewiness, springiness and gumminess were high in tofu which was made with $5{sim}15%$ SMP. Savory taste and overall acceptability of the tofu prepared with $5{sim}15%$ SMP were higher than those of control when evaluated by sensory test.