PROBLEM TO BE SOLVED: To provide a hydrogen production apparatus stopping method and a hydrogen production apparatus that can shorten the time necessary to completely stop the apparatus while preventing the deterioration of a catalyst in a reformer, and that can reduce the apparatus in size.SOLUTION: This invention provides a stopping method for a hydrogen production apparatus comprising a reformer having a modification section for generating modified gas containing hydrogen and carbon monoxide by steam modification of a hydrocarbon-containing feed gas, and a conversion section for discharging hydrogen-rich converted gas by CO conversion of the modified gas, characterized in that the hydrogen production apparatus further comprises a water electrolysis unit and the supply of the feed gas and the steam to the modifier is stopped as well as the inside of the modifier is purged by the hydrogen gas generated in the water electrolysis unit. This invention also provides a hydrogen production apparatus comprising a m
