A hydrogen generator comprises a burner for generating a combustion gas, a reformer provided around the burner to generate a reformed gas containing hydrogen by a steam reforming reaction based on 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 an evaporator having an inner tube provided around the burner, an outer tube provided around the inner tube, and a bottom plate that closes a lower portion of a tubular space formed between the inner tube and the outer tube, the evaporator being configured to evaporate water supplied to the tubular space to generate a steam to be supplied to the reformer, wherein a water absorbing member having a water absorbing capability is provided in the tubular space.