Many digital painting systems have been proposed and their quality is improving. In these systems, graphics tablets are widely used as input devices. However, because of its rigid nib and indirect manipulation, the operational feeling of a graphics tablet is different from that of real paint brush. We solved this problem by developing the MRbased Artistic Interactive (MAI) Painting Brush, which imitates a real paint brush, and constructed a mixed reality (MR) painting system that enables direct painting on physical objects in the real world.