Abstract: The present invention presents a block which by layer-building therewith, can be used to form walls so that a log house can be constructed with ease. With the present invention, rainwater which has penetrated through the areas where the blocks are linked is prevented from coming through to the inside wall side. The present invention also increases the surface area supporting the weight of the block thereby reinforcing the strength of the building. A block 1 is comprised of a hook-shaped joint 2, a linking protrusion 3, a linking groove 4, and an insertion through hole 5. A first slanting surface 31 which is slanted away from one side and toward the other side is formed in the top of the linking protrusion 3 together with a second slanting surface 32 which faces toward the one side and away from the other side. Flat surfaces 33 and 34 are formed on both ends of these slanting surfaces which are higher than each of these slanting surfaces.