To provide a gas conduit can effectively deaden or reduce flow sound caused by flow of gas by effectively using a narrow assembling space.

The gas conduit 10 includes a lead-in tube 11 for leading in gas and a lead-out tube 12 for leading out the gas. The lead-in tube 11 and the lead-out tube 12 are coupled together by a muffler 13 having a hollow part for deadening or reducing the conduction sound of the gas. A hollow part of the muffler 13 is shaped into a flat form in which a maximum value of a vertical sectional area indicative of the sectional area of a section vertical to a parallel section is smaller than a parallel sectional area indicative of the sectional area of a section parallel to a lead-in side connection surface 13a or a lead-out side connection surface 13b, and is shaped into a fan shape with a center angle of approximately 90. As a result, the gas conduit 10 can effectively deaden or reduce the flow sound of a desired frequency, and can utilize the narrow assembling space effectively.