PURPOSE: To adjust the height of the shoulder portion of a seat belt device steplessly and continuously by engaging the end portion of an anchor base which is vertically slidable along a guide rail with a coil type rotary member and rotating the coil type rotary member.

CONSTITUTION: An anchor base 3 is vertically movably installed on a guide rail 4 installed on a body pillar portion, etc. An anchor 2 is fixed to one end of the anchor base 3 to support the webbing 1 of a seat belt. The other end of the anchor base 3 is engaged with a coil type rotary member 5 provided in parallel to the guide rail 4. As the coil type rotary member 5 is rotated, the anchor base 3 can be lifted up/down steplessly and continuously being guided by the guide rail 4. Thereby, the height of the shoulder portion of the seat belt can be set to an optional height.