To provide a lever float type drain trap that facilitates maintenance of a valve seat and a valve.

A casing is constituted of a lid 4 where an inlet 1 of drain is arranged and a body 3. A hollow float 17 is vertically movably arranged inside of the body 3. The float 17 is connected to a rotating support part 8 by the lever 7. A connection rod 9 connecting the lever 7 and an on-off valve member 5 is attached to the lateral side of the rotating support part 8. The float 17 moves up and down, thereby the connecting rod 9 rotates, the torque is transmitted to the on-off valve member 5, and the on-off valve member 5 can be opened and closed. The maintenance of the valve and the valve seat can be executed without disassembling the body 3 and the lid 4 and by disassembling only the on-off valve member 5 when executing the maintenance of the valve and the valve seat incorporated in the on-off valve member 5.