A method and apparatus for measurement reporting during a conditional PCell handover in a wireless communication system is provided. A wireless device receives, from the source cell, a handover command including a handover condition for a target cell. A wireless device performs measurement on at least one of neighbor cells. A wireless device transmits, to the target cell, a handover complete message based on that the handover condition for the target cell is met, wherein the handover complete message includes results of the measurement on the at least one of the neighbor cells.