Bamboo reefs of ca. 2 m bamboos with branches were set upside-down on a tidal flat in the western part of the Seto Inland Sea on May 27, 2006. The mud temperature, the water temperature in tidepools, and the air temperature were observed as 15 minute intervals at 7 stations of the bamboo reef area during a spring low tide, on August 10. Temperatures between 2 stations under the shade of bamboo branches and 5 stations on the tidal flat without shade were compared for the maximum temperature at the surface, at a depth 1 cm in mud and in tidepools. Then, the temperature of the bamboo shaded stations was 33.4℃, 32.4℃, and 33.2℃, and the exposed stations was 36.7℃, 36.7℃, and 38.0℃, respectively. Especially, the difference between the shaded and the exposed stations was 6.3℃ in water temperature of the tidepool at 14 : 30 (the shaded was 31.6℃ : the exposed was 37.9℃).