To provide a lever float drain trap that prevents foreign matter from being deposited onto a normally-open part and automatically removes the deposited foreign matter.

A valve seat 9 with valve openings 7 and 8 opened for connecting a valve chest 6 with an outlet 2 is formed at the lower part in the valve chest 6. A lever 13 is connected to a rocking shaft 12 that is rotatably supported by a support hole 11 provided in the valve chest 6. A float 14 to be raised or lowered according to the liquid level in the valve chest 6 is connected to the lever 13, and a valve unit 17 to be separated from or seated on the valve seat 9 to open or close the valve openings 7 and 8 is connected to the lever 13. The rocking shaft 12 has a fan-shaped cross section. The support hole 11 has a fan-shaped cross section having a larger center angle than the fan-shaped cross section of the rocking shaft 12. An upper radius part 22 of the fan-shaped cross section of the rocking shaft 12 is brought into contact with the upper radius part 23 of the fan-shaped cross section of the support hole 11, to prevent the valve unit 17 from being seated on the valve seat 9, while forming normally-open gaps 24 and 25 between the valve seat 9 and the valve unit 17 on the whole surface of the seal surface of the valve seat 9.