Two forms of sea mustard, Undaria Pinnatifida were cultured in order to compare the morphological characteristics and the efficiency of production. U. Pinnatifida f. distans was collected from Wando, Korea and U. Pinnatifida f. typica was transplanted from Sanriku, Japan. The latter form grew faster in length and weight than the former. Maximum growth was shown in early April for both forms, and the growth rates decreased after this. Absolute growth rates between the two forms were quite different. Average total lengths at the harvest season was 161.1cm in U. Pinnatifida f. distans and 183.5 em in U. Pinnatifida f. typica and average weights of those two forms were 1,003.4g and 1,314.6g, respectively. The weight of available parts for the salting process of the two forms were 734.8g and 968.5g, respectively. The rates of total length versus the length of the available part of the two forms were $76\%$ and $83\%$, respectively and those of the total length versus weight of the available part of them were $43.8\%$ and $52.7\%$, respectively. The results of this study suggest that the U. pinnatifida f. typica had more available part per unit weight than that of the U. pinnatifida f. distans for the efficiency of salt processing.