Toxic PCB has been broadly used as insulating oil in electric equipment such as capacitors, transformers and the like. Since the PCB is a refractory organic compound, the disposal of PCB is not advanced until now. This is a great social problem in Japan and the world. Thus, the early disposal of PCB is demanded. The conventional PCB disposing systems include a burnout type high-temperature disposing system and a chemical decomposing system. However, the high-temperature burning system is not satisfactorily improved due to various problems such as a difficulty of control for a furnace, a problem of disposing the ash containing non-decomposed PCB, a problem of generation of dioxin in lower processing temperature, a problem of movement of the PCB and a problem of not obtaining the agreement of inhabitants. Moreover, the chemical decomposing system raises various other problems in that a plant must be constructed with a huge investment that is said to be equal to 40 hundred millions per plant, that PCB must be transported to the PCB disposing plant and that the PCB disposing speed in the plan is too slow. The present invention provides a novel PCB electrolyzing and disposing method and apparatus based on a new idea in which the PCB used as electrically insulating oil can be electrolyzed by passing the electricity through the PCB. The PCB disposing apparatus of the present invention may be portable. Thus, the apparatus can be moved to any PCB storage place to dispose the PCB in place without transportation of the PCB. In addition to the introduction of the PCB into an electrolyzing tank, the PCB may be electrolyzed by pouring water into the container of equipment containing the remaining PCB, inserting the inserting portion including the electric-wave rod, electrode rods and others into the water to electrolyze the PCB. A PCB-polluted container may be placed in a large-sized disposing tank for electrolysis. The system of the present invention may be used as a soil improving apparatus by placing PCB- or dioxin-polluted soil in a disposing tank and electrolyzing the PCB or dioxin therein. The apparatus of the present invention may be manufactured in smaller to larger sizes, depending on processing scale, and may be manufactured as a portable apparatus, as a large-scaled plant or as an integral unit mounted on a vehicle. Moreover, the system of the present invention can dispose the PCB with a greatly reduced cost and in an increased speed, in comparison with the prior art. According to the present invention, the disposal of PCB can be sharply be accelerated in Japan and the world.