Rotary-body throttle valve for spark ignition internal combustion engine

A rotary-body type throttle valve for a spark ignition internal combustion engine in which the valve comprises a valve casing 11 in the inside of which an intake passage 12a, 12b is formed with a rotary-body recess portion 12d which adopts a line intersecting a central axis 12c of the intake passage as an axis thereof being formed in the midst of the intake passage 12a, 12b, and a valve element 13 in a rotary-body shape which is rotatably fitted into the rotary-body recess portion 12d of the valve casing 11, and a communication passage 15 which makes an upstream intake passage 12a and a downstream intake passage 12b sandwiching the rotary-body recess portion 12d of the valve casing 11 communicate with each other is formed in the valve element 13. A through hole 18 which is directed from the communication passage 15 of the valve element 13 in a direction intersecting a central axis 15a of the communication passage 15 and reaches only one of rotary outer surfaces of the valve element 13 is formed in the valve element 13.