A magnetic roller device and a method for calculating rotation information thereof are disclosed. The magnetic roller device includes a multipole magnet, an MCU, plurality of Hall components, and a roller disposed on a handwriting device, wherein the multipole magnet is disposed on the roller, the multipole magnet includes at least one pair of magnetic poles with opposite polarities, and output ends of the plurality of Hall components are connected to an input end of the MCU; the plurality of Hall components are all located on a same plane of a magnetic field sensing space of the multipole magnet, and distances between each of the plurality of Hall components and the multipole magnet are equal; and a distance between two adjacent ones of the plurality of Hall components is less than half of a width of each magnetic pole in the multipole magnet.