PURPOSE: To prevent the tensile stress of a webbing from reaching the predetermined value by connecting a belt retractor and a webbing clamping means by a connecting means bent when impeding force by the webbing clamping means reaches the specified value, so as to allow the limited motion of the webbing clamping means going away from the belt retractor.

CONSTITUTION: A webbing clamping means 12 allows a webbing 28 to slidingly pass through without being damaged when the grade of belt tension indicated by an arrow mark F is 6000 N to 12000 N. A belt reel 20 is hindered from rotation relative to a clamping shoe 30 through a control claw 52, a rotating ring 48 and lever arms 42, 44, and in the case of the generation of further tension of the belt reel 20 to the webbing 28, the belt reel 20 is moved toward impeding teeth 24, 26. Stress exceeding the predetermined value of the webbing 28 is thus absorbed by the impeding teeth 24, 26 through the belt reel 20.