A body of a hydrogen generator includes a reformer configured to generate a reformed gas mainly containing hydrogen, a material passage configured to supply a reforming material, which is a material for a reforming reaction, to the reformer, a shifter configured to convert CO contained in a reformed gas obtained from the reformer into CO2, a reformed gas passage configured to supply the reformed gas obtained from the reformer to the shifter, and a passage for the shifted gas obtained from the shifter. The shifted gas passage and the material passage are adjacent to each other with a shared horizontal wall interposed therebetween, and thereby, heat from the shifted gas and radiant heat from the downstream end face of the shifter are transferred to the reforming material that travels in the material passage.