Patent ID: 7527296

Claim:
A seat belt buckle rotation angle restriction mechanism for restricting a buckle support member for a seat belt to rotate within a predetermined angle range, the buckle support member being rotatably supported by a seat support member for a vehicle, comprising: a shaft portion fixed to one of the seat support member and the buckle support member; a bearing portion provided at the other one of the seat support member and the buckle support member, the bearing portion supporting the shaft portion in such a manner that the shaft portion is rotatable; at least two rotational side surfaces provided at one of outer contact surfaces of the shaft portion and inner contact surfaces of the bearing portion, the two rotational side surfaces being symmetric about a rotational center of the buckle support member; and at least two block side surfaces provided at the other one of the outer contact surfaces of the shaft portion and the inner contact surfaces of the bearing portion, the two block side surfaces being symmetric about the rotational center of the buckle support member, each block side surface forming a predetermined angle with each rotational side surface, wherein the at least two rotational side surfaces and the at least two block side surfaces restrict the rotation of the buckle support member relative to the seat support member by engagement between at least one of the rotational side surfaces and at least one of the block side surfaces.