A method and apparatus for conditional handover based on the service time of candidate cells in a wireless communication system is provided. A wireless device receives, from a network, handover configuration including information related to candidate cells to be measured and service time of each of the candidate cells. A wireless device performs measurement on the candidate cells. A wireless device selects a cell among the candidate cells based on the service time of each of the candidate cells. A wireless device performs handover to the selected cell.