Provided is a large reboiler whereby space can be conserved and plant costs can be reduced. More specifically, provided is a large reboiler comprising a vessel where a fluid is supplied from below and evaporated gas is expelled from above, and a heat transfer pipe group disposed within the vessel such that a void penetrating therethrough in the vertical direction is formed, the maximum length of the cross-sectional shape of a flow path for the fluid being greater than 2m, wherein 5-10% of the surface area of the cross-sectional shape of the flow path is occupied by the void.
