The magnetic force acting on magnetic toner from the magnetic latent image recorded by longitudinal recording is theoretically analyzed. Heretofore analysis using sinusoidal approximation of magnetization has been reported wherein the force acting on toner can be several hundred times the force of gravity and it is not much smaller than the force used in electrostatic printing. This paper employs arctangent approximation of magnetization for digital longitudinal recording. A new approximate equation of the force attracting toner is presented which is applied to the magnetic printer using metal thin film recording medium and dry toner. Typically, the recording medium comprises Co-Ni-P plated metal thin film with the thickness of 1 micrometer. The toner comprises soft magnetic toner with the diameter of 10 micrometers. The resulting force acting on toner can be about three orders larger than the force of gravity. It is almost the same as the force used in electrophotography.