Amount of the blown sand transported from sea coastal has burried the forest stand on unduratingcoastal dune. Accumulation changes caused by the profile of coastal sand dune and the forest structure of windbreak were investigated at Sanri-Matsubara located in Fukuoka prefecture. To discribe the profile of coastal sand dune, space of top-to-top of dunes and slope of the windward surface were measured, and forest densityand tree height were measured as indicator of the forest structure of windbreak along seven line transects. Also depth of the sand burrid trees (artificial black pine) was measured as the accumulation volume on forest stand. The forest density and the tree height have independently no effect on the accumulation of blown sand. In section of higher in slope of windward surface of 1st and 2nd dunes from the sea, and shorter in space of the top-to-top of dunes, the accumulation volume increased. Moreover in the case of higher in forest density and tree height, the accumulation of blow sand was tend to still more proceed.