To provide a passage structure which can capture or remove bubbles in a liquid through a simple method and a simple arrangement and supply a liquid stably and uniformly into microscopic passages.

The passage structure is equipped with the function of capturing bubbles in a circulating liquid and has a second reservoir 28 and two or more passages communicating with the second reservoir 28. Among the passages, at least one is a supply passage 26 which supplies a liquid to the second reservoir 28, and those other than the supply passage 26 are second branch passages 30A to 30D which discharge the liquid in the second reservoir 28. A bubble-capturing mechanism which captures bubbles 64 in a second liquid L2 having been supplied to the second reservoir 28 from the supply passage 26 is arranged above the second reservoir 28.