The gaseous chlorine in the atmosphere and the water-soluble material of the aerosols collected at Owase in October 1975 were analyzed. The concentration of gaseous chlorine was found to be 3.1 µg/m3. It is found that the Cl/Na ratios inn the aerosols were always lower than that of seawater. Their mean value was 0.67. On the basis of this value, it was estimated that the amount of Cl deficiency in the aerosols was 2.1 µg/m3 which is 61% of the theoretical Cl content of sea-salt particles. The amount of Cl deficiency corresponded to the concentration of {2(So4)ex.+NO3-NH4} in the aerosols. Thus, it is suggested that the Cl deficiency is mainly due to the chemical reaction between the sea-salt particles and H2SO4 and HNO3 originated from the gaseous materials such as SO2 and No2, in the atmosphere. According to the relationship between the amount of Cl deficiency in the aerosols and the concentration of gaseous chlorine in the atmosphere, it was considered that a considerable amount of the gaseous chlorine in the coastal atmosphere at Owase was released from sea-salt particles.