The factors which are reported to cause the uneven density of roentgenogram are 1) geometrical condition, 2) sensitive material and procedures of development, 3) effect of scattering X-rays and 4) individual difference in the subjects to be photographed. By improving these difficuties to attain uniform density, the progress can be expected in the application of X-ray to wider ranges of diagnoses. For this purpose, teleroentgenography, use of low gamma film the selection of developer and use of the compensatory intensifying screen or a rectifying filter, etc. have been attempted. We have also developed a movable rectifying filter. We reported on the factors producing uneven density of roentgenogram and on the method to improve it.