A vehicle allocation control device, when a forgotten item in the vehicle is detected after setting a first travel route including a drop-off place, is configured to: calculate a first time at which the vehicle arrives at the drop-off place by travelling along the set first travel route, set at least one second travel route which is different from the first travel route and goes through a facility for depositing the forgotten item, calculate a second time at which the vehicle arrives at the drop-off place by travelling along the second travel route, and change the first travel route to the second travel route where a time difference between the first time and the second time is equal to or less than a permissible time.