Studies have suggested the importance of implementing climate change mitigation and adaptation measures in combination with considering possible co-benefit and trade-off among them. However, quantification of such co-benefit/trade-off at city scale is still its infancy. Accordingly, using a micro zone level spatial explicit land use model which we have developed, this study assesses the co-benefit of a mitigation measure (compact city policy) and an adaptation measure (retreat from high flood hazard areas) from the view point of CO2 emissions and expected loss due to the damage by river floods. For the assessment of residential CO2 emissions, this paper utilizes the microdata of the National survey of family income and expenditure. We show an example of effective compact city policy which attains co-benefit with an adaptation measure.