Abstract: 1.Experiments were conducted at Shantung Marine Cultivation Station, 1963,on the interculture of Undaria pinnatifida(Harv.)Sur.on the bamboo rafts used primarily for the cultivation of Laminaria japonica Arsch.It was proved that the method of interculture was successful in the increase of pro- duction. 2.It was reported that for a short period of 60 days'interculture,the influence to Laminaria's growth was very slight and temporary,and it was possible to produce 850 kgs.of Undaria,about equivalent to 17% of Laminaria per mou. 3.In the event of extending the intercultural period to 80 days,the yield of Undaria could be increased to 1,000～1,200 kgs.,about equivalent to 20～24% of Laminaria per mou.Although the extension of time somewhat hindered the growth of Laminaria,yet one month after the harvest of Undaria, normal growth would soon be recovered. 4.It was concluded that the intercultural method provided a favorable means for developing commercial cultivation of Undaria,inasmuch as its ex- clusive culture was not considered to be economical.