Abstract: A 5H-dibenzo [a,d] cycloheptenylidene derivative and a 5H-dibenzo [1,d] cycloheptenylidene derivative represented by the following general formula [I]: ##STR1## wherein X is --CH.sub.2 --CH.sub.2 -- or --CH.dbd.CH--; R.sub.1 and R.sub.2 are alkyl groups, aralkyl groups, aromatic groups or heterocyclic groups, R.sub.3 and R.sub.4 are hydrogen atoms, alkyl groups, alkoxy groups or halogen atoms; and Ar.sub.1 is an aromatic group or a heterocyclic group, process for producing those derivatives, and electrophotographic photosensitive member using the same.