A forming device that forms a metal pipe by heating and expanding a metal pipe material includes: a pair of an upper die and a lower die between which the metal pipe material is heated and expanded; upper electrodes and lower electrodes that sandwich both end parts of the metal pipe material therebetween from upper and lower sides to heat the metal pipe material; and a busbar that is connected only to either the upper electrodes or the lower electrodes to supply electric power from a power supply.