The present invention provides a wire harness for an electrically heated catalyst, which efficiently dissipates heat from the catalyst while preventing damage to the wires in advance. The wire harness for the electrically heated catalyst of the present invention is connected to a catalyst box containing a catalyst for purifying the exhaust gas of an internal combustion engine and arranged on the exhaust gas pipeline for discharging the exhaust gas. The wire harness for the electrically heated catalyst is characterized in that it comprises: wires, connected to a power source; And the electrode body is used to relay and connect the box side terminals and wires set on the catalyst box, and to dissipate the heat transferred from the heated catalyst to the box side terminals. According to this structure, the wires are connected to the box side terminals of the catalyst box through the electrode body, so the heat transferred from the heated catalyst to the box side terminals is dissipated into the air in the electrode body. Therefore, the heat from the catalyst can be efficiently dissipated to prevent damage to the wires in advance