A roof opening/closing apparatus for operating a roof of a vehicle to move between first and second positions includes a panel member for covering an upper portion of an accommodating space and a panel moving mechanism. The panel member includes a first panel and a second panel which are aligned in a longitudinal direction of the vehicle. The panel moving mechanism is provided under the panel member to movably support the first and second panels. The panel moving mechanism includes a sliding mechanism slidably moving the second panel relative to the first panel so that the first and second panels are overlapped when the roof is located in the first position and a length of the panel member in a longitudinal direction of the vehicle is reduced to be smaller than the length of the panel member when the roof is located in the second position.