This study introduces the details of carbonation test for cross-section cutting-off girder of an actual bridge which is used for predicting the service (remaining) life of the bridge. Service (remaining) life prediction is crucial as a kernel of the systematization for the bridge maintenance. An existing bridge is generally exposed to various environmental conditions during their period of service life. Therefore, the deterioration due to carbonation has a possibility to occur and it will have a significant effect on the service life of the bridge. Chloride ion attack should be considered as another factor of deterioration if the bridge is closed to the sea. This study proposed the concept of service (remaining) life prediction of an aged bridge due to carbonation and chloride attack. Also, present the flowchart according to this concept to estimate the service life prediction. The results show that the main deterioration factor is carbonation with the presence of corrosion in the reinforcing bar and chloride ion affected the deterioration of the bridge as well.