1. A radiographic apparatus for obtaining radiographic images, comprising: radiation emitting means for emitting radiation toward an object under examination; signal sampling means for taking radiation detection signals from radiation detecting means at predetermined sampling time intervals; and time lag removing means for obtaining lag-free radiation detection signals by removing said lag-free radiation detection signals from the respective radiation detection signals by a recursive computation, on an assumption that a lag-behind part included in each of said radiation detection signals taken by said signal sampling means at the predetermined sampling time intervals is due to an impulse response formed of one exponential function or a plurality of exponential functions with different attenuation time constants; said radiographic images being derived from said lag-free radiation detection signals obtained by said time lag removing means.