This study proposes a greedy-based approximation algorithm to determine the route of a land leveler, which is a type of agricultural machine for leveling and flattening the surfaces of fields. First, we describe the definition and the formulation of the land leveler problem (LLP) and show the exact solution based on dynamic programming for solving the LLP. Second, we propose the approximation algorithm and compare three visit functions which are used in the algorithm. Third, the comparison between the approximation algorithm and the exact solution is shown. Fourth, we apply the approximation algorithm to measurement data of a real field. Finally, we verify the validity of the movement constraint which is assumed for computing the route.