A ventilation and air-conditioning apparatus comprising: a casing provided with a supply-air intake port and a discharge-air blowout port on outside of a room, and a discharge-air intake port and a supply-air blowout port on inside of a room; a supply-air passage formed in the casing to lead from a supply-air intake port to a supply-air blowout port; a discharge-air passage formed in the casing to lead from a discharge-air intake port to a discharge-air blowout port; a heat exchanger that performs heat exchange between air currents flowing through the supply-air passage and the discharge-air passage; a bypass passage formed in the casing in parallel to the discharge-air passage to bypass the heat exchanger and to lead from the discharge-air intake port to the discharge-air blowout port; a supply-air blower that takes in outdoor air from a supply-air intake port and supplies the outdoor air into a room from a supply-air blowout port; a discharge-air blower that takes in indoor air from a discharge-air intake port and discharges the indoor air from a discharge-air blowout port to outside of the room; a passage switching unit that is provided between the discharge-air passage and the bypass passage and that switches whether to pass indoor air taken in from a discharge-air intake port through the heat exchanger; a temperature sensor that is provided between the heat exchanger and the supply-air blowout port and that measures a temperature of air supplied to a room; and a control unit that controls the supply-air blower, the discharge-air blower, and the passage switching unit (12, 13), and a temperature adjustment unit that is provided on a side of a downstream of the heat exchanger in the supply-air passage and that heats or cools air in the supply-air passage, characterized in that the control unit controls the passage switching unit (12, 13) to adjust a degree of opening of the bypass passage in a range from 0 to 100% based on an output of the temperature sensor so that a temperature of air supplied to a room approaches a predetermined temperature and the control unit, when the temperature of air supplied to a room does not reach the predetermined temperature by adjusting the bypass passage, then starts to control the temperature adjustment unit so that the temperature of air supplied to the room approaches the predetermined temperature. a casing provided with a supply-air intake port and a discharge-air blowout port on outside of a room, and a discharge-air intake port and a supply-air blowout port on inside of a room; a supply-air passage formed in the casing to lead from a supply-air intake port to a supply-air blowout port; a discharge-air passage formed in the casing to lead from a discharge-air intake port to a discharge-air blowout port; a heat exchanger that performs heat exchange between air currents flowing through the supply-air passage and the discharge-air passage; a bypass passage formed in the casing in parallel to the discharge-air passage to bypass the heat exchanger and to lead from the discharge-air intake port to the discharge-air blowout port; a supply-air blower that takes in outdoor air from a supply-air intake port and supplies the outdoor air into a room from a supply-air blowout port; a discharge-air blower that takes in indoor air from a discharge-air intake port and discharges the indoor air from a discharge-air blowout port to outside of the room; a passage switching unit that is provided between the discharge-air passage and the bypass passage and that switches whether to pass indoor air taken in from a discharge-air intake port through the heat exchanger; a temperature sensor that is provided between the heat exchanger and the supply-air blowout port and that measures a temperature of air supplied to a room; and a control unit that controls the supply-air blower, the discharge-air blower, and the passage switching unit (12, 13), and a temperature adjustment unit that is provided on a side of a downstream of the heat exchanger in the supply-air passage and that heats or cools air in the supply-air passage, characterized in that the control unit controls the passage switching unit (12, 13) to adjust a degree of opening of the bypass passage in a range from 0 to 100% based on an output of the temperature sensor so that a temperature of air supplied to a room approaches a predetermined temperature and the control unit, when the temperature of air supplied to a room does not reach the predetermined temperature by adjusting the bypass passage, then starts to control the temperature adjustment unit so that the temperature of air supplied to the room approaches the predetermined temperature.