A pressurized fluid injecting sleeve (10) to be mounted on a lock bolt main body (1) is composed of a cylindrical large-diameter projection (11) and a small-diameter washer holder (12), the outer diameter of the washer holder (12) being smaller than the hole diameter of a washer (6). It is desirable that the large-diameter projection (11) and washer holder (12) be equal in inner diameter. With the lock bolt main body (1) embedded in bedrock or ground, the washer (6) is seated on the edge of a lock bolt insertion hole, while the washer holder (12) extends into the lock bolt insertion hole. Therefore, the members projecting from a sprayed concrete layer disposed on the bedrock or ground are only the washer (6) and large-diameter projection (11). The height of projection is restrained, and thereby, the placing of lining concrete can be easily done to make reinforcing work of high reliability possible.