A burner having a secondary air regulator is provided. The secondary air regulator has an end plate having a bored hole penetrating in an axial direction and for forming a cylindrical space with peripheral surface opened in a space with the furnace core side surface of the wind box, a rotary damper having a bored hole penetrating in an axial direction and being capable to open or close the hole on the end plate by rotating in a peripheral direction, a sliding damper for surrounding the cylindrical space and being slidable in an axial direction, air vanes installed at a predetermined distance along circumference of the cylindrical space and for giving swirling to the secondary air, first driving means for rotating the rotary sliding damper, and second driving means for sliding the sliding damper.