Recent increase in seawater temperature has caused coral mortality in global scale, leading disruption of the tropical ocean ecosystem. One of the main reason of heat induced coral death is the loss of symbiotic dinoflagellates of family Symbiodiniacea (called as “coral bleaching”). Such algal loss from coral tissue is a result from either or both decrease in algal uptake speed and increase in their algal release speed. However, how these two factors contribute to the bleaching has been unknown. In this study, we examined the effect of increased temperature on the algal uptake using cnidarian model organism, sea-anemone Exaiptasia pallida with two cultured algal strains, CCMP2459 and CS-164. The infection of algae into the host polyps was significantly suppressed by increased temperature in both strains, but more severely with CS-164. We then compared the bleaching sensitivity between sea-anemone polyps associated with CCMP2459 or CS-164. The algal density declined under increased temperature in the polyps with CS-164, but not with CCMP2459. Our results suggest the heat-induced inhibition of algal uptake is one of the contributors of the bleaching phenomena.