Using photostimulated transient current measurements, the charge transport mechanism involved in the imaging process of particle migration microfilm has been elucidated. It was found that the illumination of a microfilm, across which an electric field had been applied, results in photogenerated electron‐hole pairs which separate within the Se particles followed by charge injection out of the particles across the Se‐styrene hexylmethacrylate interface. This injection results in negatively charged Se particles due to the more efficient transfer of holes relative to the electrons. The excitation spectrum of the Se spheres within the microfilm reflects the photoresponse of bulk amorphous Se which agrees with the photographic sensitivity of the particle migration microfilm.