RETAINING WALL BLOCK

PROBLEM TO BE SOLVED: To allow zigzag stacking when executed on a slope face of a curved surface in a retaining wall block having a front wall, two or more buttresses, a back face wall, and a bottom plate, having a projecting part projecting forward from a front face of the front wall, arranging an upper end opening vegetation material housing space in the projecting part, and forming the lower end of the space as a structure that a root of a plant can extend to a body filling material of a brace part of a lower stage block. SOLUTION: A projection 21 is arranged on an upper surface of the back face wall, and a slit-like hole 23 for fitting this projection is arranged in the bottom plate, and is formed in the shape of having clearance 17 between the projecting part 14 and a back face of the front wall 11 of the lower stage block 10a forward from the front wall 11 of an upper stage block 10b in a state of fitting this projection 21 and the hole 23.