A fuel supply device includes a flange unit and a pump unit. The flange unit includes a flange main body for closing an opening formed in an upper wall of a fuel tank. The pump unit includes a joint member that is connected to the flange main body so that both components may be movable relative to each other in the vertical direction. The interval in the vertical direction between the flange main body and the joint member is restricted from going below a minimum vertical interval. The minimum interval occurs when a stand-off portion provided as part of the flange main body and a connecting plate portion provided as part of the joint member come into mutual contact with each other and abut each other in the vertical direction.