PURPOSE: To make copying of a key difficult by pressing a rotor pin by a movable pushing member, drawing the rotor pin within a passage of a cylinder barrel and constituting a rotor so as to be rotatable when the key having the movable pushing member is inserted into a housing.

CONSTITUTION: When a key main body 3 of a key 1 is inserted into a housing 4, an end 14 of a movable pushing member 9 presses a tip part 19 of a rotor pin 12 and a bolt 18 is drawn into a passage 17 of a cylinder barrel 7. A rotor 5 rotates for the cylinder barrel 7 and operates a lock. Further, when the key main body 3 is pulled from the housing 4, the bolt 18 projects within a passage 16 of the rotor 5 and the rotor 5 is fixed to the cylinder barrel 7.