Patent ID: 7426774

Claim:
A buckle device provided with a tongue plate connected to a webbing, and a buckle body through which the insertion and release of the tongue plate is implemented, characterized in that the buckle body comprises a frame, a hook member rotatably provided on the frame, rotatable at the time of insertion of the tongue plate to engage with the tongue plate, and always urged in a direction to release the engagement thereof, a release button for implementing the release of engagement between the hook member and the tongue plate, a lock bar moving to a position for allowing the rotation thereof in the direction to release the engagement of the hook member while being pushed by the release button at the time of engagement releasing operation of the release button, and moving to a position where the rotation thereof is restrained in the direction to release the engagement of the hook member by an urging force of an urge member in a state of engagement with the tongue plate, a lock member rotatably pivotally supported by the frame between a lock position where the lock bar is locked and an unlock position where the lock bar is unlocked, and the urge member for elastically urging the lock member toward the unlock position, wherein the lock member comprises a base end part pivotally supported by the frame, a first engagement part formed on substantially the central portion of the base end part, a second engagement part formed opposite to the first engagement part while leaving a space through which the lock bar can be received, and a third engagement part provided opposite to the second engagement part and capable of entering a movement area of the release button, and wherein in a state where the lock member is positioned at the lock position, the lock member is rotated toward and held at the lock position when the lock bar is butted against the first engagement part, thereby causing the second engagement part to enter a movement area of the lock bar, while in the case where an inertial force in a direction of the insertion of the tongue plate is exerted at a value exceeding a predetermined value, the release button is butted against the third engagement part, thereby preventing the lock member from being rotated toward the unlock position to hold the lock position.