A work planner includes a divider and an adjustor. Based on action information including a plurality of first actions indicating work units that involve one executor or a plurality of executors including a robot and that start at respective defined start timings, the divider is configured to divide one action among the plurality of first actions that involves the plurality of executors into a plurality of second actions corresponding to the respective plurality of executors. Based on dependency information indicating a relationship of dependency among the plurality of first actions including the plurality of second actions, the adjustor is configured to adjust a start timing of at least one of third actions, among the plurality of first actions, that involve an identical executor.