a fusion welding device include : a first holder , having a first face , and adapted to hold at least an outer peripheral face of an end portion of a first work in a state where the first work is movable in a longitudinal direction thereof ; a second holder , having a second face opposed to the first face , and adapted to hold at least an outer peripheral face of an end portion of a second work in a state where the second work is movable in a longitudinal direction thereof ; a heater , operable to heat the first and second works ; a first and second movers , adapted to move the first and second holders in such directions that the first and second faces come close to or apart from each other ; and a third mover , adapted to move the first and second holders in synchronization with each other in a direction along the first and second faces . the first and second holders are moved by the third mover in a state where the first and second faces are in contact with each other , whereby end faces of the end portions of the first and second works are pressed to each other in the longitudinal directions thereof in the first and second holders .