The present investigations were made with the purpose of elucidating the seasonal variation in total nitrogen content of Gelidium amansii. Monthly samples were collected from the sea near pusan, from August 1957 to June 1959. The results obtained have been summarized as follows: The maximum total nitrogen content of Gelidium amansii was observed during the months of January and February, and the minimum content was observed in June and July Thus the total nitrogen content of Gelidium amansii exhibited a considerable periodic change throughout the year. The recommended harvest time of Gelidium amansii with regard to total nitrogen content, is from May to October, but on the other hand the proper harvest time is from May to June, with respect to the season of spore-formation and its propagation.