TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Components: Upon starting supply of feed material from material feed portion to the reformer, the water is supplied from the water supply portion to the reformer via the second water passage. After an elapse of predetermined time, the water is supplied from the water supply portion to the evaporator via the first passage and the supply of water to the reformer is stopped. The reformer has a reformer-temperature-measuring portion for detecting temperature of reforming catalyst or temperature of gas inside the reformer, and the supply of feed material from material feed portion and supply of water from water supply portion are controlled, based on the detected temperature information. When the detected temperature is larger than a preset reference value, the water is supplied to the reformer and the feed material is fed to the reformer. When the detected temperature is larger than a preset second reference value which is greater than the first reference value, the water is supplied to the evaporator and the supply of water to the reformer is stopped. The evaporator has an evaporator-temperature-measuring portion for detecting temperature of evaporator or temperature of gas inside the evaporator, and the supplies of water to the reformer and evaporator, respectively, are controlled based on the detected temperature information. When the detected temperature is smaller than a preset reference value, the water is supplied to the reformer. When the detected temperature is larger than the reference value, the water is supplied to the evaporator. The evaporator includes a heater, a first evaporator placed in contact with the reformer to evaporate the water supplied to the reformer, and a second evaporator connected to the water supply portion through the first water supply passage to evaporate the water supplied to the reformer. The water supply portion has a water supply switch for switching water destination between the reformer and evaporator. The switch is capable of adjusting flow rate of water. At a time when supply of the feed material to the reformer starts, at least one of the water and steam exists in the reformer and/or evaporator.