To provide a pilot type steam trap capable of preventing slanting of a piston.

The pilot type steam trap includes a trap casing formed of a body 1 formed with an inlet 4 and an outlet 6 and a lid 2, a valve port 14 formed between the inlet 4 and the outlet 6, a valve element 17 disposed in an inlet side of the valve port 14 and opening and closing the valve opening 14, the piston 16 disposed in an outlet side of the valve port 14 and driving the valve element 17, a pressure chamber 10 formed in one face of the piston 16 in a side opposite of the valve port 14, a first orifice 11 communicating the pressure chamber 10 with an inlet side, a second orifice 20 communicating the pressure chamber 10 with an outlet side, a pilot valve 9 opening and closing the first orifice 11 and controlling a pressure in the pressure chamber 10 to operate the piston 16, a bulkhead tube 21 separating an outlet side space 7 between the valve port 14 and the piston 16 and the outlet 6, and communication holes 22 plurally formed on the bulkhead cylinder 21 with a total opening area the same as a valve port area, the communication holes 22 are formed only in both sides in a perpendicular direction to the outlet 6.