Climate change, along with the increase of severe weathers and natural disasters, is becoming an important factor to consider for infrastructure investments. To adapt infrastructure to the effects of climate change, new design, construction, or rehabilitation methods-so-called adaptation methods-can be deployed. However, it is crucial to understand the impact of adaptation methods on infrastructure before they are actually implemented. When the economic benefit and cost are clear, asset managers can confidently make informed decisions about the priority of investment alternatives. This paper proposes an integrated algorithm to assess the benefit and cost of adaptation methods. The "integrated" aspect of the algorithm is derived from the fact that climate change effects on infrastructure can be divided into two categories. One is sudden extreme weather events caused by climate change; this sudden event leads to swift and disruptive damages to infrastructure. The other is a gradual climate change of which effects are shown over a long period of time. The algorithm combines the two different aspects of climate change to estimate the net benefit of adaption methods in an integrated manner. Future climate scenarios are first assumed and their input variables are determined for further procedures. With extreme events such as supertyphoon, the procedure for sudden failure of infrastructure is used to estimate the cost and benefit of the rehabilitation effort. Maintenance cost under gradual climate change is also estimated with the climate change adjusted deterioration curve for the infrastructure of interest. Finally, the above three steps are repeated for each year to estimate the life cycle cost infrastructure adaptation to climate change for the comparison of the costs with and without adopting the adaptation method.