A micro-mixer includes a plurality of fuel tubes through which air and fuel flow, a casing accommodating the plurality of fuel tubes therein, and a plurality of injection parts each formed as a pyramidal protrusion on one side of the casing and connected to a front end of the fuel tube to inject the air and the fuel, wherein each of the plurality of injection parts has an inclined injection hole formed obliquely with respect to an extension direction of the plurality of fuel tubes on at least one side of the pyramidal protrusion.