Abstract: To reduce the weight of a staircase block so as to be manually carried and installed, prevent adjacent blocks from being displaced from each other after installation, and prevent the blocks from being raised and separated from each other due to heating and cooling by conquering problems with the staircase blocks related to publicly known technologies. In this precast concrete block for building a staircase, large recesses (2) and (9) are formed in the rise surface (1) and the rear surface (8) of the block to reduce the weight, and displacement prevention grooves (7) for connecting the adjacent blocks to each other with mortar are formed in the side faces of the block, and round parts (partially cylindrical recessed surfaces) (10) with a specified radius are formed at the inner corner parts of the recess (9) in the rear surface so that an acute angle part preventing the adhesive mortar from being filled therein is not produced.

Abstract: To reduce the weight of a staircase block so as to be manually carried and installed, prevent adjacent blocks from being displaced from each other after installation, and prevent the blocks from being raised and separated from each other due to heating and cooling by conquering problems with the staircase blocks related to publicly known technologies. In this precast concrete block for building a staircase, large recesses (2) and (9) are formed in the rise surface (1) and the rear surface (8) of the block to reduce the weight, and displacement prevention grooves (7) for connecting the adjacent blocks to each other with mortar are formed in the side faces of the block, and round parts (partially cylindrical recessed surfaces) (10) with a specified radius are formed at the inner corner parts of the recess (9) in the rear surface so that an acute angle part preventing the adhesive mortar from being filled therein is not produced.