To provide a small cremorne lock to facilitate mounting of it on an opening and closing panel.

A simplex cremorne bolt comprises a cremorne bolt housing 1 containing a door knob hole 14 rotated in a 90°, a rack 16 engaged with a saw tooth 17 formed in a peripheral part 14a of the door knob hole 14, and a support body 15 to support two protrusions 8 fixed at the respective rods of a cremorne bolt. The maximum diameter of the door knob hole 14 is substantially equal to the width of the housing 1. A slot 18 is formed in the longitudinal side wall 1a of the housing 1, and the second peripheral part 14b of the door knob hole 14 has a radius substantially equal to a distance between the axis of the door knob hole 14 and the side wall 1a of the housing 1.