Heat exchanger

A heat exchanger comprising:

• a pair of header tanks formed in parallel and spaced apart from each other by a predetermined distance;
• a plurality of tubes fixed to the pair of header tanks at both ends to form a flow channel of a refrigerant;
• and
• a fin interposed between the tubes,
• wherein the plurality of tubes are extruded tubes, and when each tube is formed such that a tube width is greater than a tube height and a flow channel in the tube is divided into a plurality of holes formed in parallel of the tube in a width direction by a plurality of inner walls extending in a height direction of the tube, the tube width, an outer wall thickness at an end portion of the tube in the width direction, a hole width, and an inner wall thickness have a size within a range in which the following formula is satisfied:
• 2.5<A/B<4 Formula 1:
• (Here, Tw:
• tube width, Tn:
• outer wall thickness at end portion of tube in width direction, A:
• hole width, B:
• inner wall thickness).