A lock (4) for an antitheft device (1) for a steering column of a motor vehicle, comprising: - a stator (5) extending along a main axis (6) and having at least two parts (5a; 5b), - a control device (7) housed inside the stator (5) and comprising a rotor (9) extending along the main axis (6), said control device (7) being configured to take up a locking position and an unlocking position of the steering column when said rotor (9) is rotated about the main axis (6), - at least two securing assemblies (11a; 11b), of which each securing assembly (11a; 11b) is disposed between the control device (7) and the parts of the stator (5a; 5b) and is configured to keep the parts of the stator (5a; 5b) secured to the control device (7) when the control device (7) is in the locking position and to allow the rotor (9) to rotate freely when the control device (7) is in the unlocking position.