Abstract: A lock core device of an anti-theft tumbler pin type includes a housing defining a lock core hole, a plurality of first tumbler pin holes, at least one side tumbler pin hole, and a transverse hole, a lock core rotatably mounted in the housing and defining a plurality of second tumbler pin holes which are moved by the lock core to align with the first tumbler pin holes and to align with the side tumbler pin hole, a plurality of tumbler pin sets each slidably mounted in the first tumbler pin hole and each including a top tumbler pin and a bottom tumbler pin movable in the second tumbler pin hole, at least one block pin slidably mounted in the side tumbler pin hole and rested on a peripheral wall of the lock core or inserted into the second tumbler pin hole, and a control tumbler pin set slidably mounted in the transverse hole and including a transverse tumbler pin rested on the block pin.