We investigated the influences of salinity on growth of two strains of Pyropia tenuipedalis selected in low salinity condition (approximately 3 salinity). At the different salinity conditions of seawater concentrations (0, 25, 50, 75 and 100%), original, a month selection and four months selection strains were able to grow under 25 ‒ 100% (approximately 8‒32 salinity) seawater conditions, particularly it had well growth under 75% condition. The growth of original and a month selection strains under 100% condition were better than those under 50% condition. On the other hand, the growth of four months selection strain under 50% condition was better than that under 100% condition. Therefore, it was thought that four months selection strain had tolerance to the lower salinity in comparison with the original and a month selection strains. Moreover, it was thought that the cell selection technique in the present study was useful for Pyropia breeding.