To provide a locking mechanism for a door which has a simple constitution, of which the movable sections are comparatively little, of which the manufacture and the assembly are easy, and also, which has less troubles.

A grip (1) which is formed over the total area in the vertical direction on the edge section on the opposite side from a hinge of the door (50) is equipped with a sleeve-like housing section (11) at least on one of the top and bottom ends. The sleeve-like housing section (11) houses a lock pin housing member (2) which becomes the rotating shaft of the grip (1) and is fixed to at least one of the top and bottom ends of the door (50). The lock pin housing member (2) is urged upward or downward by an elastic means (4), and also, houses a lock pin (3) which is constituted to be movable in the vertical direction. Then, a converting mechanism which converts the turning of the grip (1) into the downward or upward movement of the lock pin (3) is provided.