The present invention discloses a foldable electrical junction box for lighting apparatus comprising a base board formed by a metal plate, and four side boards disposed peripherally around the base board; the four side boards are rotationally mounted on the base board which is rectangular in shape; the four side boards comprise two long side boards and two short side boards; the long side boards and the short side boards are rotationally mounted on long sides and short sides of the base board respectively; at an open state, the two long side boards and the two short side boards are rotated outwards to form a box with the base board which is open on top and has a hollow cavity; at a folded state, the two long side boards and the two short side boards are rotated inwards to fold on the base board to form a flat rectangular body.