PURPOSE: To prevent a housing of a lock main body from turning easily when a burglar is trying to turn an outside lever handle forcibly beyond the upper limit of a backward movement of a latch sliding member.

CONSTITUTION: In a door lock where an inside lever handle 3A and an outside lever handle 4A are mounted to a lock main body 5A incorporated in a door 1A and a pull-in motion of a latch bolt 9 of a latch 8 installed to a latch shaft 11 which intersects with a handle shaft is made by the rotary motion of the inside shaft 27A or the outside rotary shaft 28A of a lock main body 5A, a plurality of twist-counter measure engagement parts 5 are formed on a housing 7A of the lock main body 5A. On one hand, a plurality of engagement rods 77, which are engased with the engagement part 51, are fixedly installed to an inside fixing plate 17A which is pierced into an internal wall surface 1b of the door 1A.