In this paper, we deal with modeling the optimal maintenance schedule for track irregularities. Through appropriate maintenance activities at ballasted track, railway track irregularities must be kept at a satisfactory level with the optimal cost. In practice, however, most maintenance strategies focus only on sustaining railway track irregularities at an allowable limit, as they are difficult to treat quantitatively. In order to determine effective maintenance strategies, we developed a mathematical programming model for an optimal schedule of multiple tie tamper (MTT) operation based upon both maintenance costs and the level of surface irregularities that reflect riding quality and safety. By using the model, we can obtain the optimal tamping schedule with an MTT. The schedule indicates the divisions for which tamping must be executed in a specified term (10 days). Then, we apply the model to an assumed railway network and confirm that it is effective and useful from the results of the application.