A task management system for executing a task selected from tasks structuring a task combination, includes a judging unit for judging whether there is a task combination switchover request or not, a switchover unit for switching over the task combination after completing an execution of a specified task in the tasks structuring the task combination before the switchover when judging that there is the switchover request, and an execution unit for executing the task selected from the tasks structuring the task combination switched over by the switchover unit.