The present invention relates to a cold reserving heat exchanger, and more particularly; to a cold reserving heat exchanger capable of improving cooling comfortableness of a user and minimizing energy and a time consumed at the time of again performing cooling by storing a cold reserving material in a second-row tube among tubes disposed in three rows in a width direction and allowing a cooling fluid moving in a first-row tube and a third-row tube among the tubes to be movable between the first-row tube and the third-row tube to effectively store cold air of the cooling fluid and discharge the cold air at the time of stopping an engine to thus prevent a rapid rise in an internal temperature of a vehicle.