An electrical connection box includes an insulating plate made of resin that supports an input load applied on a connection terminal to be connected to an electrical part. The insulating plate is contained between upper and lower cases and provided with a honeycomb structure portion penetrating through the insulating plate in a plate thickness direction. It thus becomes possible to provide an electrical connection box of a novel structure provided with an insulating plate not only ensuring strength with a smaller amount of resin but also capable of enhancing heat dissipation.