To provide a float type steam trap which is compact and has a large capacity in a low-pressure state.

A valve casing having a valve chest 3 in the interior is formed by a body 1 having an inlet 4 and an outlet 6 and a lid 2 fastened to the body 1. A first valve port 7 communicating the valve chest 3 with the outlet 6 is provided. The first valve port 7 is directly opened and closed by a float 9 disposed in the valve chest 3. A second valve port 18 communicating the valve chest 3 with the outlet 6 is provided. In the valve chest 3, a flat plate-like pressure respond member 14 where the inlet 4 side fluid pressure acts in the valve closing direction and the outlet 6 side fluid pressure and the elastic force of a coiled spring 15 acts in the valve opening direction is disposed to open and close the second valve port 18. The first valve port 7 is formed with dimensions so that the corresponding float 9 can open the valve over the total working pressure range, and the second valve port 18 is formed with dimensions so that the corresponding pressure respond member 14 can open the valve only in a predetermined low pressure range.