Abstract: An air-proportionality type boiler is provided. Since the air-proportionality type boiler directly controls a current proportionality gas valve according to an amount of air by using a low-price AC air blower, a low-price current proportionality gas valve and a low-price airflow sensor, a gas supply amount can be adjusted with respect to all ranges of the airflow amount. Also, an appropriate calorie required for proportionally controlling a present circulation water temperature to a set temperature, can be supplied. The boiler can be safely ignited to perform a combustion operation under the optimal condition although abnormal weathers and conditions. Accordingly, since a combustion performance is enhanced, combustion efficiency is high and a fuel cost can be saved.