Provided is a heat exchanger. The heat exchanger may include a plurality first through third heat exchange pipes connected between a first side part and a second side part, each of which comprising a path of moving heat-exchanger fluid inside; first blisters formed on the outer side surfaces of the first side part and the second side part, thereby connecting gaps between each neighboring first heat exchange pipe; second blisters formed on the outer side surface of the first side part, thereby connecting the first heat exchange pipes with the second heat exchange pipes or the second heat exchange pipes with the third second heat exchange pipes; and third blisters formed on the outer side surface of the second side part, thereby connecting neighboring second heat exchange pipes or neighboring third heat exchange pipes. The second heat exchange pipes may be spaced apart from the first heat exchange pipes and formed above the first heat exchange pipes and the third heat exchange pipes may be spaced apart from the second heat exchange pipes and formed above the second heat exchange pipes.