An imaging-plate X-ray area detector which utilizes photostimulable phosphor (Ba FBr: Eu2+) originally developed for diagnostic radiography, has a detective quantum efficiency of more than 80 % for 8 ~ 20 keV X-rays, a 1:105 dynamic range, a spatial resolution of 150 μm full width at half maximum and no instantaneous count-rate limitation. A readout system for imaging plates has been developed for the purpose of X-ray diffraction studies by modifying a drum-type densitometer. Two apparatus for time-resolved measurements have also been developed. The first one is based on a cinema method which permits 40 exposures of a two dimensional X-ray pattern (100 mm x 108 mm) with a 0.3 s time resolution. The second one works as a 200 mm-long linear detector which enables a time resolution of 23 μs for a duration of 46 ms, based on a streak-camera method.