A liquefied-gas vaporizer to be installed in a ship is an Open-Rack-type liquefied-gas vaporizer equipped with vertically-installed heat exchange panels (6) and troughs (10A and 10B) that are installed at top side portions thereof and that make a heating-medium fluid (W) overflow from overflow openings (18) so as to flow on the heat exchange panels, thus gasifying liquefied gas in heat transfer pipes (5), and the overflow openings of the troughs have edge portions (18a) that are disposed adjacent to the heat exchange panels and that the heating-medium fluid (W) flows over to the exterior when overflowing from the overflow openings and edge portions (18b) that are positioned on the opposite side from the heat exchange panels with the edge portions (18a) positioned therebetween, and the height of the edge portions (18b) in the vertical direction is greater than the height of the edge portions (18a) in the vertical direction.