In a hydrogen generation device according to the invention, PSR reformers have a heat capacity smaller than that of the other PSR reformers. Therefore, the temperature of the catalyst reaches to a reforming-start temperature more quickly in the PSR reformers than in the other PSR reformers. When the hydrogen generation device is started and the reforming reaction is carried out, the mixture of gasoline vapor and water vapor is selectively and preferentially supplied to the PSR reformers so that the reforming reaction is carried out in the PSR reformers.