To provide a closing mechanism of a door, putting the normally closed door in the open state and pressing the normally closed door to a door frame by pushing and pulling a handle without rotating.

A latch mechanism 4 includes: a hook member 6 mounted on the door frame 2; and an engaging member 7 mounted on a door 3 and engaged and disengaged with and from the hook member 6. An operating handle 5 mounted on the door 3 is pushed and pulled to thereby releasably link the engagement of the hook member 6 and the engaging member 7. In the closing state of the door, the door 3 can be pressed to the door frame 2 taking an engagement part 7a of the engaging member 7 and the hook member 6 as a fulcrum by the pressing operation of the operating handle 5. Further, the latch mechanism is provided with a non-return member 13a for checking the return rotation of the engaging member 7 while the door is pressed.