FluxPaper is a new paper-based medium that enables physical movement and dynamic interaction between a high-power magnetized paper and a programmable magnetic field. FluxPaper has a very thin patterned magnetic layer (0.1 mm) pasted behind the paper. A thin but strong neodymium-based magnet realizes fast, powerful, and precise physical actions while retaining the original characteristics of the paper that is widely used in our daily lives. Owing to an effective magnetic pattern and a computer-controlled magnetic field, FluxPaper can add new interaction modality to ordinary paper. We describe the functions of magnetized paper; challenges through realization; and the interaction scenarios in several applications, such as self-alignment, self-construction, floating on the board, and quickly picking out a target card from a stack.