A forming system that forms a metal pipe by expansion in a die includes a heater that heats at least an end part of a metal pipe material, a fluid supply unit that supplies a fluid into the metal pipe material to expand the metal pipe material, and a controller that controls the heater and the fluid supply unit, the fluid supply unit has a nozzle that supplies the fluid from the end part of the metal pipe material into the metal pipe material, and the controller controls the heater so as to heat the end part of the metal pipe material at least before the supply of the fluid by the fluid supply unit, and controls the fluid supply unit so as to expand the end part of the metal pipe material.