To provide a lock having improved crime preventing effect by providing a cylinder in an indoor side, in regards to an inter-grip rim lock to be used for an entrance of a multiple dwelling house and an apartment house, to solve the problem wherein the number of crime is increased and crime becomes more fearless and vicious and any strong lock is ineffective against intrusion by drilling a door and turning an indoor side thumb-turn with a hand to open the door.

The cylinder is provided in an indoor side of an inter-grip rim lock case so that the fitting/removal of the lock to/from the door and fitting/removal of the cylinder are impossible as long as the door is closed. With this structure, even if an intruder drills the door and put a hand inside the door, the door can not be unlocked without a duplicate key.