The present invention provides a pipe structure including: a pipe through which a gaseous body having a higher temperature than a temperature of a surrounding atmosphere flows; a cover that covers an outer peripheral portion of the pipe, and defines a plurality of vents from which the gaseous body leaking from the pipe flows out; and a line-shaped sensor that passes a position corresponding to each of the plurality of vents, and is sensitive to a temperature or a concentration of the gaseous body outside the cover, wherein the sensor includes a range in which the sensor rises upward from the position corresponding to the vent.