1. A construction progress visualization system, comprising of: a CAD model storage unit for storing a 3D CAD model of a construction object; a construction schedule storage unit for storing construction schedule data; a scaffolding model creating-unit for creating an area and a form of scaffolding required for a construction operation based on the 3D CAD model and the construction schedule data; a scaffolding schedule extracting-unit for extracting scaffolding schedule data regarding the scaffolding from the construction schedule data in the construction schedule storage unit; a scaffolding display form determining-unit for determining a completion rate of the scaffolding on a visualization-target date based on a relationship between the visualization-target date and the scaffolding schedule data, and obtaining a display form of the scaffolding; and a display process unit for generating display information of the CAD model, and display information of the scaffolding area based on the obtained display form of the scaffolding.