A steam trap comprises: a main body having a flow path between an inlet and an outlet; an opening and closing unit, installed at an outlet of the main body, and an operation unit, installed in the flow path between the inlet and the outlet, wherein the opening and closing unit is provided with a nozzle that has a discharge hole, and includes an opening and closing member which is in close contact with the nozzle at the inlet side of the flow path for blocking or opening the discharge hole while linearly moving, and an operating rod for connecting the operating unit and the opening and closing member to linearly move the opening and closing member to the operating unit.