A workflow defining system comprises a state setting module, an instruction generating module, and a path generating module. The state setting module sets at least a first terminal state, a second terminal state, and a third terminal state. The instruction generating module generates a first instruction, a second instruction, and a third instruction respectively corresponding to the first, second, and third terminal states. The path generating module generates a first path, a second path, and a third path respectively according to the first, second, and third instructions. The first path according to the first instruction points to one of the first, second, and third terminal states. The second path according to the second instruction points to one of the first, second, and third terminal states. The third path according to the third instruction points to one of the first, second, and third terminal states. Furthermore, a workflow managing system is disclosed, and performs workflow management according to a workflow defined by the workflow defining system.