Micro-bubble generating device and swirl flow generating device

A micro-bubble generating device (10) wherein a hole (12) that longitudinally penetrates the main body (11) thereof is formed. A gas/liquid mixing space (16) using one side of the hole (12) as a nozzle (15) is arranged therein, and a liquid supply unit (17) is provided at the other end. A swirl flow-forming body housing space (19) that houses a swirl flow-forming body (18) is provided between the gas/liquid mixing space (16) and the liquid supply unit (17). A pair of annular protruding sections (184, 185) are provided on the outer peripheral surface of an outer peripheral section (181) of the swirl flow-forming body (18), and both sides of the pair of annular protruding sections (184, 185) are hermetically sealed using O-rings (25, 26). In the main body (11), a horizontal hole (13) is provided at a position corresponding to an annular space (22) partitioned in an air-tight manner by the protruding sections (184, 185), and a gas flow path that passes through the gas/liquid mixing space (16) is provided in the