A caridean shrimp Palaemon macrodactylus was reared in aquaria, and frequency of spawning during a breeding season, growth and survival were observed. Spawning was carried out five to nine times for I+ females and once or twice for 0+, and suspension of breeding for a long time was found late in the breeding season. Contrary to the hypothesis proposed previously by a number of Japanese fisheries biologists, death of 0+ spawner, even if they had spawned, was not observed. I+ females which had suspended breeding carried ripe eggs in their ovaries at the end of rearing experiment. This recovery of ovaries shows that another spawning would occur after long suspension of breeding. On the other hand, 0+ did not reproduce ripe eggs after stopping spawning, though they still adapted themselves to spawning morphologically. The life historical traits show that the females which spawn at age 0+ seem to make much reproduc-tive effort, producing eggs once or twice for a short time, while those of I+ and II+ make a little reproductive effort, spawning five to nine times during a long season. This reproductive mode would be a kind of mixed reproductive strategy.