Polychlorinated biphenyls (PCBs) have been prohibited for two decades in Japan and Taiwan. The aim of this study was to compare the PCB congeners in maternal and cord serum between two countries. Our study subjects were 248 and 100 mother-child pairs in Japan and Taiwan. The measured levels of 23 serum PCB congeners between two countries were analyzed using gas chromatography–electron capture negative ionization quadrupole mass spectrometry (GC-NICI-qMS). The statistical comparisons were conducted by Student's t-test and principal component analysis with further stratification by maternal age and parity. The maternal total PCBs levels in Japan (426 ± 244 pg/g wet wt) were significantly higher than those in Taiwan (254 ± 155 pg/g wet wt), and the similar results were found in cord total PCBs levels (97 ± 76 and 58 ± 87 pg/g wet wt). It showed different distributions of PCB congeners between two countries. Whether in maternal or cord serum, the CB138, CB153 and CB180 were the highest detectable congeners whether in Japan or Taiwan. And, the CB66, CB99, CB206 and CB209 were only detected in maternal serum of Taiwan. The women of advanced maternal age had higher levels of PCB congeners, especially in Taiwan, and the primiparous women had higher levels of PCB congeners in two countries. In summary, the PCB congeners in Japan's mother-child pairs were with higher levels and different distributions when compared to those in Taiwan, and the maternal age and parity were important factors associated with the PCB levels.