Surveillance of vector mosquitoes has been conducted in Tokyo since 2004, and Aedes albopictus and Culex pipiens complex were identi ed as the dominant and widely-distributed species in Tokyo Metropolis. We performed PCR-based identi cation of the Cx. pipiens complex that we collected using CO 2 baited-traps from 25 sites in Tokyo Metropolis area between 2018 and 2019. In 2019 mosquito larvae were collected from catch basins at 9 sites, reared to adult, and a part of the emerged Cx. pipiens comlex were identi ed by PCR-based method. As a result, Cx. quinquefasciatus and the hybrids between Cx. quinquefasciatus and Cx. pipiens complex (excluding Cx. quinquefasciatus) were identi ed in Tokyo Metropolis area for the rst time. Continuous eld survey is required whether Cx. quinquefasciatus have already been distributed or not in Tokyo Metropolis.