Hydrogen generation system and fuel cell system having the same

A hydrogen generation system comprises a reformer 1 that contains a reforming catalyst, an evaporator 4 that supplies steam to the reformer 1, a heater 3 that heats the reformer 1 and the evaporator 4, a material feed portion 5 that feeds a feed material containing hydrocarbon compound to the reformer 1 through the evaporator 4, and a water supply portion 6 that has a flow rate switch 6a and supplies water to the reformer 1 and the evaporator 4.