An electrical junction box includes an insulating substrate, a bus bar that is bonded to the insulating substrate, and a reinforcement plate that is bonded to a region of the insulating substrate to which the bus bar is not bonded. The reinforcement plate includes a through hole that allows passage of a shaft portion of a screw. A heat-dissipating member is stacked on a surface of the reinforcement plate opposite to the insulating substrate, and includes a screw hole into which the screw is screwed. A retaining member retains the respective positions of the insulating substrate, the bus bar, and the reinforcement plate, and the reinforcement plate includes an engagement portion that aligns the through hole and the screw hole by engaging with the retaining member.