Dryer and controlling method thereof

A dryer comprising a belt conveyor for conveying a first material to be dried;

• a heating device for generating a high temperature gas to dry said first material;
• a first supply part provided to supply the high temperature gas heated in said heating device toward the belt of the belt conveyor;
• a second supply part provided to supply the high temperature gas heated in the heating device to the ceiling side of the space in which the belt conveyor is located;
• a first circulation part for recovering air between said belt conveyer and said ceiling and circulating it to the heating device;
• and
• a second circulation part for recovering the gas passing through said ceiling side and circulating it to the heating device.