POWER RELAY ELECTRIC CONNECTION BOX WITH COOLING FOR AN ELECTRIC VEHICLE

An electric connection box 10 that has a function of relaying power of power supply supplied from an input-side power supply line and supplying the relayed power of power supply to an output-side load on a vehicle, that includes a first circuit unit (power conversion unit 20), a second circuit unit (power supply control unit 30), and an air blower (cooling unit 40) configured to blow air to the first circuit unit, and in which the first circuit unit and the second circuit unit are arranged in a state of being close to each other, the electric connection box 10 includes: a gap portion (50) that is a space formed on a boundary between the first circuit unit and the second circuit unit; and an airflow guide portion (a cover 44, a bottom plate portion 41a, and side plate portions 41b and 41c) configured to guide an airflow blown by the air blower to both the first circuit unit and the gap portion.