An oral cavity cleaning tool for the purpose of sterilization of the inside of oral cavity is provided that carries out efficient sterilization by using effective chlorine that is obtained through electrolysis. The oral cavity cleaning tool comprises a block handle, a head section extending from the block handle, a pair of electrodes provided on the head section and a power source that supplies electric current to the pair of electrodes, wherein the electrodes are put into contact with an oral fluid that contains chloride ions thereby to cause electric current to flow between the electrodes, so that the chloride ions are transformed into effective chlorine.