The breeding season of the bivalve, Lamprotula coreana , was observed in the vicinity of Achun-Ri of the Han River under the natural conditions. The effect of temperatures on spawning and attaching periods of the glochidia was also investigated in the laboratory. 1. The breeding season of Lamprotula coreana was lasted from October to April in the next year. The glochidia of Lamprotula coreana were observed in the outer gill layers, therefore they beling to the exobrachiae. 2. Each spawning of glochidia of Lamprotula coreana ended within 15, 12 , 7 and 5 days at 1$0^{circ}C$, 15$^{circ}C$, 2$0^{circ}C$ and $25^{circ}C$of water temperatures respectively. 3. The attaching period of glochidia of the Lamprotula coreana onto fish was longer at a low temperature than at higher one.