of the spring 40 is supported by a pin 41 fixed near the rear end 33b of the slot 33 the retractor 5 is placed at a central portion of the floor 7 fig1 a preferably the retractor 5 is positioned just behind a parking brake not shown for the purpose of improving comfortableness of a rear seat the port 5a of the retractor 5 is formed in a stepped portion of the housing 5b of the retractor 5 and preferably in parallel with the seat cushion 9 so as to prevent friction or the like between the belt 1 and the port 5a of the retractor 5 when the belt 1 is pulled or reeled the operation of this embodiment of the present invention will be explained fig1 and 15 show the case in which the seat back 19 is in its normal upright position in this case the lever 25 is disposed such that the pin 35 engages the front end 33a of the slot 33 in this position the guide arm 13 rests against the stop 39 the spring 40 is loosed as the seat back 19 is tilted forward in fig1 the lever 25 is pulled since the pin 35 is in contact with the end 33a of the slot 33 the pin 35 is also urged which causes the guide.