Shock-proof device, buckle having the shock proof device, and seatbelt apparatus having the buckle

A shock-proof device to be disposed in a buckle, comprising:

• a latch member for engaging a tongue,
• a release button associated with the latch member for releasing the tongue from the latch member, said release button comprising a button-side first engagement connection part and a button-side second engagement connection part,
• an inertia lever comprising a pair of opposed rotation shafts and a lever-side engagement connection part, said lever-side engagement connection part abutting against the button-side first engagement connection part and the button-side second engagement connection part to prevent the release button from moving in a release direction of the release button, and
• a torque-difference generating device for generating a torque difference between a first torque and a second torque applied to the inertia lever, said first torque being applied to the inertia lever by an inertial force of the release button in the release direction when the inertial force of the release button in the release direction is applied to the release button and the inertia lever so that the release button abuts against the inertia lever, and said second torque being applied to the inertia lever by an inertial force of the release button in a non-release direction when the inertial force of the release button in the non-release direction is applied to the release button and the inertia lever so that the release button abuts against the inertia lever.