NOVELTY - Hydrogen generator comprises a burner, a reformer, and an evaporator having inner and outer tubes provided around the burner and a bottom plate that closes a lower portion of a tubular space formed between the inner and outer tubes. The evaporator evaporates water supplied to the tubular space to generate the steam to be supplied to the reformer. A water absorbing member is provided in the tubular space.    USE - The hydrogen generator is used in a fuel cell system (claimed).    ADVANTAGE - The hydrogen generator has a simple configuration, high evaporation capability, and high heat efficiency.    DETAILED DESCRIPTION - Hydrogen generator comprises:    (i) a burner (3) for generating a combustion gas;    (ii) a reformer (26) provided around the burner to generate a reformed gas containing hydrogen by a steam reforming reaction from a feed material comprising a compound containing at least carbon and hydrogen and a steam using heat transmission from a combustion gas generated by the burner; and    (iii) an evaporator having an inner tube (33) provided around the burner, an outer tube (34) provided around the inner tube, and a bottom plate (35) that closes a lower portion of a tubular space formed between the inner tube and the outer tube.    The evaporator is configured to evaporate water supplied to the tubular space to generate the steam to be supplied to the reformer. A water absorbing member having a water absorbing capability is provided in the tubular space.    An INDEPENDENT CLAIM is also included for a fuel cell system comprising a hydrogen generator and a fuel cell configured to generate a power using an oxidization gas containing oxygen and the reformed gas supplied from the hydrogen generator.    DESCRIPTION OF DRAWING(S) - The figure is a cross-sectional view schematically showing a configuration of the hydrogen generator.    Burner (3)    First evaporation chamber (14)    Second evaporation chamber (15)    Reformer (26)    Inner tube (33)    Outer tube (34)    Bottom plate (35)