WEBBING HEIGHT ADJUSTING UNIT AND WEBBING HEIGHT ADJUSTING DEVICE

A webbing height adjusting device and a webbing height adjusting unit (3) thereof is applied in a three-point seat belt system (1). The webbing height adjusting unit (3) has an adjuster base (30), a slider (40), an elastic member (50) for actuating the adjuster base (30) and the slider (40), and an outer shell (60) disposed on the adjuster base (30). The webbing height adjusting device has a supplementary webbing (2A) and a D-loop (2B) connected to each other. The webbing height adjusting unit (3) is connected to a main webbing (1A) to form an adjustable top position and clamps the supplementary webbing (2A). The adjuster base (30) and the slider (40) are simple and convenient in operation to unclamp the supplementary webbing (2A) and adjust a height position of the webbing height adjusting unit (3).