To provide a cylinder lock for a building, which dispenses with provision of key pieces having different shapes corresponding to different cylinder locks.

According to the cylinder lock 1 for the building, by protruding a plurality of tumblers 8a, 8b arranged in an axial direction into a tumbler engaging groove 4 formed in a holder 2, rotation of a cylinder main body 3 arranged in the holder 2 is disabled, to thereby lock a door of the building. On the other hand, by withdrawing the tumblers 8a, 8b into the cylinder main body 3 upon insertion of keys 30, 31, the rotation is enabled, to thereby unlock the door. In the cylinder lock 1, at least one of the tumblers 8a, 8b is a user tumbler 8b which recedes into the cylinder main body 3 upon insertion of the key 31 having a long body, and the user tumbler 8b has an engaging hole 13 formed therein at a predetermined location. Further, the cylinder lock is comprised of a holding member 20 for holding the user tumbler 8b in a receding position upon insertion of the key 31 into the engaging hole 13.