Abstract: The micro bubble generator comprises a gas-liquid generating tank and an outer shell tank and the space there between is configured as a channel for the liquid. A plurality of liquid supply ports are provided in the channel and supply liquid through the channel into the gas-liquid generating tank from the liquid supply ports. Inside the gas-liquid generating tank, a swirling flow is generated by the supplied liquid and a negative pressure cavity is thereby generated near the axis of the cylinder axis. From the gas supply portion, gas is supplied from the outside by the action of the negative pressure cavity or by additionally forcing the gas supply. The supplied gas is formed into micro hubbies by the swirling liquid flow and is discharged from the gas-liquid outlet discharging port as a gas-liquid.