Abstract: The invention concerns a chronograph mechanism of the type comprising a chronograph train (22) including: a coupling lever (16) for ensuring the movement of a coupling wheel, between a first position in which the mechanism is operating and a second position in which the mechanism is not operating, and a control lever (26) activating the coupling lever (16) to make it pass from one position to another. In this mechanism, the control lever (26) carries a locking member (36) and the coupling lever (16) a catch (20) cooperating with the locking member when the coupling wheel (14) occupies its first position, such that the coupling lever (16) is prevented from moving via the effect of a shock when the chronograph is operating.