The long-term trend of the partial pressure of CO2 in surface seawater (pCO2sea) in late-January to early-February during the past two decades was examined in the western North Pacific along the repeat line at 137¿E from 3¿N to 34¿N. The growth rate of pCO2sea at each 1¿ in latitude ranged from +1.3 ¿ 0.2 to +2.1 ¿ 0.3 ¿atm yr-1, and the average was +1.7 ¿ 0.2 ¿atm yr-1. The growth of pCO2sea is attributable mainly to the uptake of anthropogenic CO2 in surface water and, to a small extent, to the regional changes in sea surface temperature (SST). The net air-to-sea CO2 flux in January--February that accounts for 40 to 60% of the annual flux remained at a similar level in the subtropical regions (7¿N to 34¿N). In the equatorial region (3¿N to 6¿N), however, a slight increase in the CO2 efflux was seen.