Poly [1, 5-dipheny1-3-( p -vinylphenyl)-pyrazoline], a photoconductive polymer, was prepared from polystyrene via polyvinylacetophenone and polyvinylbenzalacetophenone. Especially, the relation between the preparation conditions in the last step and the content of unreacted vinylbenzalacetophenone units was investigated in detail. Quantitative analyses by IR spectra showed that the photoconductive polymer contained the unreacted units at least about ten weight percent even when prepared at the optimum condition. Application of the photoconductive polymer to electrophotography was studied by coating it with or without spectral sensitizers on aluminum foil, measuring the sensitivity to incandescent light and copying images. Electrophotographic layers having comparable sensitivity with ones consisting of binder resin (polyolefine) and 1, 3, 5-triphenyl-pylazoline, a low molecular weight model substance, were obtainable.