A timetable planning system 1 includes a storage device 13 and a computing device 11. The storage device 13 stores evaluation index improvement degree information 320 that stores relations between a change of each constituent element of an operation timetable on one hand and a change in quality of the operation timetable resulting from the change of each constituent element in terms of each operation timetable viewpoint on the other hand. The computing device 11 performs a changeable timetable element selection process of selecting the operation timetable constituent element that most improves the quality of the operation timetable, in reference to the evaluation index improvement degree information, an optimization model selection process of selecting, from among multiple timetable generating models each capable of generating the operation timetable, the timetable generating model that most improves the quality of the whole operation timetable through the change of the selected constituent element, and a timetable optimization process of generating a new operation timetable based on the selected timetable generating model.