A heat exchanger and a method of manufacturing the same are provided. With the method, a tube may be inserted into a through hole formed in at least one fin coated with a filler metal, and the tube and a fin collar of the at least one fin may be joined through the filler metal by a brazing processing. A flange may not be formed on or at a top of the at least one fin collar, which protrudes vertically from a central longitudinal plane of the at least one fin. The tube may be made of aluminum (Al), and an interval between an outer circumferential surface of the tube and an inner circumferential surface of the fin collar of the at least one fin may be approximately 0.1 mm or less. Accordingly, contact resistance occurring when fabricating a fin-tube heat exchanger using a mechanical tube expansion method may be reduced, and heat transfer performance of the heat exchanger may be improved because grooves formed within the tube may not be deformed.