Abstract: A block of this invention for constructing a retaining wall is characterized by having a front wall portion of a rectangular shape, a rear retaining portion extending rearwardly and perpendicularly from the front wall portion and a gnarl-like uniting portion integrally formed at the distal end of the rear retaining portion. The block is further provided with vertical elongated holes through which reinforcing bars pass at least at a position where the front wall portion and the rear retaining portion merge and in the gnarl-like uniting portion. Due to such construction, when the blocks are stacked up in rows and the soil for land creation is charged in the spaces, each of which is defined by the front wall portion, the rear retaining portions and the gnarl-like uniting portion to form a retaining wall, such retaining wall can show increased integrity and stability against earthquakes, vibrations or flood disasters.