PURPOSE: To eliminate defects such as instability of electric charge, transfer fogging, image collapsion and tailing by incorporating a compd. having an amino group at the nitrogenous heterocyclic nucleus and ether compd. having a polyoxyethylene group into a highly insulating carrier liquid.

CONSTITUTION: The compd. having the amino group at the nitrogenous heterocyclic nucleus and the ether compd. having the polyoxyethylene are incorporated into the highly insulating carrier liquid. The heterocyclic compd. to be usedis preferably expressed by the formula and acts as an electric charge controlling agent to lender good positive electric charge to toner particles. The charge stability thereof is extremely good. The nitrogenous heterocyclic compd. having the amino group is preferably used with a measure of 0.001W0.5pts.wt. by 100pts. wt. carrier liquid. The ether compd. having the polyoxyethylene group contains a material known as a nonionic surface active agent or anionic surface active agent.