A continuous x-ray generation simulator is proposed for analyzing x-ray generation processes at the target of a microfocus x-ray tube. The cross section for braking radiation shown by Heitler is integrated by the numerical method and introduced into the Monte Carlo calculation on electron scattering. In addition to electron trajectories, the x-ray generation points and energies of x rays are calculated through the use of random numbers. By calculating the distribution of x-ray generation points for a reflective-type target and a thin film target, the thin film target is demonstrated to be necessary in obtaining a minute focal spot size. A prototype x-ray imaging system was therefore developed using a thin film target to achieve a high resolution of 1 mum. Electron beams are focused to within 0.8 mum by two magnetic lenses and applied to a two layer film target consisting of 1 mum thick tungsten and 10 mum thick beryllium.