To provide a gas-liquid mixing apparatus for mixing a large quantity of air in liquid.

This gas-liquid mixing apparatus 1 is provided with a liquid passage 2 through which liquid is made to pass, the first fluid injecting passage 3 communicated with the passage 2 for injecting a fluid, the first air introducing passage 5 communicated with the passage 3 for introducing air into the passage 3, the second fluid injecting passage 4 communicated with the passage 2 for injecting the fluid into the passage 2 and the second air introducing passage 7 communicated with the passage 4 for introducing air into the passage 4.