A nozzle-type steam trap including a venturi nozzle, an orifice nozzle, or a tunnel structure resistance nozzle minimizes the outflow of steam even when a pressure difference between a drain-water inlet and a drain-water outlet of each nozzle fluctuates, the steam trap being compatible with any usage environments and enabling maintenance and inspection to be easily performed. The nozzle-type steam trap including the venturi nozzle, the orifice nozzle, or the tunnel structure resistance nozzle includes a means for sealing the nozzle by using a drain water. The nozzle-type steam trap further includes a plurality of steam inflow ports and drain-water outflow ports and includes a closure means for determining, for a selected one of the steam inflow ports and a selected one of the drain-water outflow ports, passages of steam and drain water. More preferably, the steam trap includes a swirl flow formation means in the vicinity of the nozzle.