Cylinder lock

A cylinder lock has a cylindrical sleeve in which lock grooves are formed on an inner circumferential surface, a cylindrical cylinder on which a plurality of tumbler insertion holes are formed, a plurality of tumblers which are engaged with the lock grooves in an advanced position and which are retracted and disengaged from the lock grooves with insertion of an authorized key, a rear rotor of which at least a portion is turnably placed in the cylinder and in which a container portion is formed in the portion placed in the cylinder, a connecting member which is placed in the container portion of the rear rotor and which is movable in radial directions between a connected position in which the rear rotor and the cylinder are connected to each other and a non-connected position, and a connection releasing member positioned on an outer circumference of the connecting member and is movable in radial directions relative to the sleeve. The connection releasing member travels radially and presses and moves the connecting member to the non-connected position when the sleeve that receives a turning force of the cylinder by virtue of engagement of the tumblers turns relative to the holder.