A task management device includes a control unit that calculates a required time for maintenance of an internal environment of at least one vehicle to be operated in a mode corresponding to an application before the mode of the at least one vehicle is switched from a first mode to a second mode based on information acquired from any one of a first target to be transported by the at least one vehicle in the first mode and a second target to be transported by the at least one vehicle in the second mode that is different from the first mode, and adjusts a dispatch schedule of the at least one vehicle in accordance with the required time calculated.