An apparatus for preventing moisture condensation includes a fuel cell stack and an enclosure in which the fuel cell stack is disposed. A heater and a temperature sensor are provided in the enclosure. A controller is configured to control the heater to be turned on when an insulation resistance between the fuel cell stack and the enclosure is less than a preset resistance value. The controller controls the heater not to be turned on when a surface temperature of the enclosure measured by the temperature sensor exceeds a preset temperature.