Micro-flow passage structure and micropump

Provided are a micro-flow passage structure and a micropump capable of stably feeding liquid by preventing air bubbles from occurring when the liquid is charged or air bubbles from remaining in a micro-flow passage by a simple configuration. The micropump comprises a main member (20) in the front surface of which the micro-flow passage (a chamber (21), restricted flow passages (22), (23), flow passages (24), (25)) is formed and an upper cover (11) for covering the front surface of the main member (20).  The bottom of the chamber (21) is driven by a piezoelectric element (30) to feed liquid in the forward and reverse directions.  The charge of the drive liquid into the micro-flow passage is performed by sucking the air in the micro-flow passage through an outlet (13) and introducing the air thereinto through an inlet (12).  The solid-liquid surface energy of the main member (20) is smaller than that of the upper cover (11).  The solid-air surface energy of the main member (20) is larger than that of the upper cover (11).