This study investigated the variations in monthly PM2.5 concentrations and their characteristics at the sampling site (35.075°N, 129.080°E) around the Busan seaport area for six months (from August 2020 to January 2021). Monthly PM2.5 concentrations in the filtered samples ranged from 8.4 to 42.3 ㎍/m3 (average=19.6±8.2 ㎍/m3, n=50) and were generally high in August, December, and January, and low in September, October, and November. The variations of monthly PM2.5 concentrations showed similar patterns to those of the neighboring national air quality monitoring sites. The contents of Total Carbon (TC), Organic Carbon (OC), Elemental Carbon (EC), and OC/EC ratios in PM2.5 showed large variability during the study period. The OC/EC ratios ranged from 4.2 to 34.4, suggesting that the relative contributions of OC and EC to the PM2.5 concentrations changed temporally and might be related to their formation sources. Variations in the chemical components of and particle size distributions in PM2.5 showed that high PM2.5 concentrations were affected by various sources, such as sea salt and ship emission. The precursor gas concentrations were discussed in terms of monthly variations and their contributions to PM2.5 concentrations. However, further research is needed to understand the characteristics and behaviors of PM2.5 concentrations around the Busan seaport area.