Disclosed is an electric junction box in which a pair of cassette blocks is arranged at intervals to each other in a component-attaching direction, capable of downsizing without increase of the number of component. The electric junction box comprises a pair of cassette blocks, configured to attach electric components thereto, arranged at intervals mutually in a component-attaching direction; and a cross-sectionally U-shaped bus bar attached to one cassette block, electrically connected to the electric components, a middle of the bus bar being arranged in a direction perpendicular to the component-attaching direction, both ends of the U-shaped bus bar being arranged in the component-attaching direction, wherein the electric components attached to the other cassette block are opposed to the middle of the bus bar.