To silence the sound of closure of a bonnet.

A striker engagement groove 2 for a striker 10 fitted to a bonnet is formed at the middle position between the right and the left of a base plate 1 made of metal and a latch 3 which rotates in engagement with the striker 10 at the time of closure is fitted axially on either the right or left side of the striker engagement groove 2, while a ratchet 4 being fitted elastically with the latch 3 and preventing reverse rotation of the latch 3 is fitted axially on the other side of the groove. The base plate 1 is provided with a half latch body 14 which prevents a bonnet from opening directly even when the ratchet 4 in the state of closure is separated from the latch 3. In this case, a part of the half latch body 14 is formed to be a steep slope wall 18, which is made to face the striker engagement groove 2 so that it projects thereinto. When closure is made, the striker 10 slides in friction on the slope wall 18, the half latch body 14 is made to rotate and a half latch engagement pawl 16 is displaced to a working position where it closes up the striker engagement groove 2.