An intake and exhaust system for preventing generation of condensed water may include: an exhaust gas recirculation (EGR) system circulating some of combustion gas from an exhaust pipe to an intake pipe; an active purging system compressing and supplying evaporation gas generated from a fuel tank to the intake pipe; and a controller to control the EGR system and the active purging system. In particular, the controller calculates a saturated water vapor pressure based on temperature at a position between the EGR system and the intake pipe, and calculates a saturated water vapor pressure based on temperature of the intake pipe and then compares one of the two saturated water vapor pressures with a water vapor pressure of intake air so as to reduce an EGR rate of the EGR system or a purging rate of the active purging system based on the comparison result.