This study was performed to investigate some quality characteristics of 새려 prepared from soybean milk and various seaweed(Undaria pinnatifida, Laminaria japonica, Porpyra tenera, Enteromorpha sp., Codium sp.) pulps in the ration of 9:1(v:v) with 20% MgCl2. The yields of tofu containing Undaria pinnatifida, Laminaria japonica, or Enteromorpha sp. increased but porphyra tenera, Codium sp. decreased in comparison with tofu prepared from whole soybean milk. The protein content of tofu containing Undaria pinnatifida, Laminaria japonica, Porphyra tenera, or Codium sp. increased but Enteromprpha sp. decreased in comparison with the tofu prepared from whole soybean milk. The content of Ca in Undaria pinnatifida, Porphyra tenera added tofu was higher than that of the tofu prepared from whole soybean milk or other seaweeds added tofu. In sensory evaluation the texture, color, taste of tofu were favored with the addition of sea mustard(Undaria pinnatifida) pulp than that of the tofu prepared from whole soybean milk or tofu prepared other seaweed. Tofu prepared was possible with adding 0.5~1.5% sea mustard to soybean milk but the feasible added amount level was 1% of sea mustard. The yields, protein Ca, and K content of tofu were increased by the more adding amount of sea mustard tan tat of the tofu prepared from whole soybean milk. The hardness values of 1% sea mustard added tofu were decreased than that of the tofu prepared from whole soybean milk ; on the other hand, elasticity, cohensiveness, gumminess and brittleness of tofu with sea mustard increased. The L and a values of tofu were lower and b values were higher with the addition of 1% sea mustard. The content of histidine, tyrosine, leusine, and phenylalanine were decreased but the other amino acid were increased in tofu prepared from 1% sea mustard pulp added to soybean milk. The saturated fatty acid and monoene fatty acid content of tofu were increased and C18:2, C18:3(${gamma}$), C18:3, C20:5 of polyene fatty acid were slightly decreased in tofu prepared from 1% sea mustard pulp added to soybean milk.