The present invention provides a negataively chargeable charge controlling agent to control a charged state of a powder or granular material such as toner for electrophotography, where the agent comprises a polyhydroxyalkanoate having at least one kind of 3-hydroxy-ω-carboxyalkanoic acid unit represented by the chemical formula (1):
wherein n is an integer selected from 1 to 8; R1 is an H, Na or K atom, or
and when more than one unit exists, n and R1 is the same or different between the units. The charge controlling agent is excellent in electrophtographic properties and propitious to environment because of the biodegradability of the polyhydroxyalkanoate.
wherein n is an integer selected from the range shown in the same chemical formula; R1 is an H atom, Na atom, K atom, or
and when more than one unit exists, n and R1 may differ from unit to unit.