Carbon, nitrogen and phosphorus contents of cultured Nori (Porphyra yezoensis) that were sampled from Saga sea region of Ariake Bay, were measured. Carbon, nitrogen and phosphorus contents of the frond were 42.6±2.3, 8.6±0.8, 0.32±0.01μg-at mg DW^<-1> respectively, and the ratio was C:N:P=132:26:1