Abstract: A ventilation apparatus includes a casing having the inside partitioned into a first floor and a second floor. A first sharing duct is formed in the first floor and configured to suck one of indoor air and outdoor air and to have the sucked air horizontally moved. A second sharing duct is formed in the second floor and configured to suck the other of indoor air and outdoor air and to have the sucked air horizontally moved. First and second heat exchangers are disposed in the first and second sharing ducts, respectively. The ventilation apparatus is advantageous in that air resistance is minimized, horizontally moving air is subject to heat exchange with the entire area of the heat exchanger, and efficiency of heat exchange between air and the heat exchanger is improved because air is divided into the first floor and the second floor and horizontally moved.