Hydrogen forming apparatus, fuel cell system and method of controlling hydrogen forming apparatus

A method for controlling a hydrogen generating apparatus comprising:

• a reformer which performs a reforming reaction using a material and steam to generate hydrogen-containing gas,
• a water evaporator which generates said steam supplied to said reformer,
• a first water pathway through which reforming water to be supplied to said water evaporator flows,
• a first pump which supplies said reforming water to said water evaporator,
• a second water pathway branching from said first water pathway on the downstream side of said pump or branching from said first water pathway on which said is disposed,
• a first water tank to which the water flowing through said second water pathway flows,
• a first valve provided on said second water pathway, and
• a second valve provided on said first water pathway,
• said method comprising the step of operating said first pump and performing control to open said first valve and to close said second valve so that said reforming water delivered from said first pump flows into said second water pathway in the case that said reformer does not perform operation for generating hydrogen-containing gas or before said reforming water is supplied to said reformer.